Bob Haggart (N0CTV) has been steadily improving the workspace of the science trailer at the Plishner radio telescope site. During the pulsar observation work on May 2, 2020, he completed building his latest enhancement: a partitioned work space at the east side of the science trailer. There is desktop space, which can be used for electronics building and testing. And there is additional shelf space, for better organization and storage.
Plishner Antenna Site Work Trip Report. By Gary Agranat. Photos by Steve Plock.
Ed Corn, Steve Plock, and Gary Agranat traveled to the Plishner antenna site in Haswell this past Saturday, October 19, 2019. The team completed erecting the 50-foot ham radio tower.
Completing the tower erection involved several tasks:
Installing the 3-band/3-element Yagi HF ham antenna,
Installing the 2-meter band vertical antenna on top of that mast. This will be our new antenna for our VHF talk-in radio system.
Installing two stand-off bracketed supports near the top of the tower on the sides, to raise and hold the 80 meter band and 160 meter band dipole wire antennas. This arrangement replaces the long pole that previously centrally supported those wire antennas. These bracket supports each have a pulley and rope, to raise and lower the wire antennas. The tower also supports a 6-meter band delta-loop antenna, which is simply tied from height.
Securing the coax cables for the Yagi and vertical antennas along the side of the tower.
Properly arranging the system of wires, coaxes, and support cables.
Raising the 50-foot tower, which involves turning the winch system that rotates the tower up from its pivot plate at its base. The 50-foot tower is raised from a pulley system on a second smaller adjacent tower.
Once the 50-foot tower is raised, securing 3 guy cables.
Steve tested the SWR of the 3-band Yagi antenna with an analyzer. The antenna elements had been measured and assembled on a previous trip, to be optimized for the middle of each of the operating bands, of the 10, 15 and 20 meter bands. Steve measured an SWR ratio of 1:1 (perfect) at 28.51 MHz for the 10 meter band, and 1:1 at 21.19 MHz for the 15 meter band. The 20 meter band resonated with an SWR of 1:1.35 at 14.16 MHz. This is excellent, and as expected.
For lunch, Steve treated us with smoked ribs from Broken Bones BBQ in Monument, with sauces, potato salad, and coleslaw. Gary brewed coffee. Also, the team met first at the firehouse in Ellicott. Gary baked orange-cranberry muffins. We ate our muffins at the firehouse, and shared the rest with the fire department crews there.
The tower should significantly improve our capability to communicate long distances on the 10, 15, and 20 meter bands with the Yagi. The 2 meter band vertical should enable us to communicate on our talk-in VHF radio system to much further out.
DSES Participants: Gary Agranat, Ed Corn, Bob Haggard, Bill Miller, Steve Plock.
Ed, Gary, and Bill met first at the Ellicott Fire Department, while Steve and Bob each traveled ahead solo. Ed encountered a problem with his truck and had to return home, but he passed the tower antenna mast and connector supplies to Bill. Steve and Bob arrived at the site by 9 AM, and Bill and Gary arrived by 10 AM.
We encountered light drizzling rain and low clouds on the route to the site, but the rain let up once we were on Highway 96 past Ordway. Steve called Ed to let us know the weather was good at the site. The weather completely cleared later, while the temperature remained comfortable.
Steve coordinated by phone with Skip Crilly and commenced a 48-hour long SETI drift scan at -7.5 degrees declination, run simultaneously with Skip’s antenna in New Hampshire. The 48 hour run will scan the -7.5 degree declination band twice, and therefore acquire a repeat set of data that can be compared with the first set.
Bob worked at the Communications Trailer, doing carpentry and painting work. He built a wood frame seal around one of the air conditioners, fabricated and painted a seal for the solar-powered fan, and painted the third work table he had added previously. Bob told me the trailer back door hadn’t been sealing — until recently — because it actually had not been closed properly. He closed the door properly and it is now sealed, without requiring further work.
Bill, Steve, and Gary worked on preparing the 50-foot ham radio antenna tower.
Bill spliced the controller feed cable and wires for the antenna rotator, and verified proper operation, with some assistance from Gary. Bill used Steve’s crimping tools. The three of us then fed the controller cable through the dog house to the tower.
At the tower outside, the rotator was attached to its base plate, and that assembly was then attached to the tower.
When we tried to fit the mast in the holding tube at the top of the tower, we found that top opening was slightly damaged, and the mast wouldn’t fit in. We then took turns filing and grinding out the hole until the mast did fit properly. Steve applied a lubricating grease, to mitigate against the mast binding stuck when rotating. Eventually we successfully installed the mast to the rotator itself. We also retrieved a guy wire cable left at the communications trailer and attached it as the third guy wire connection for the top of the tower.
Before we left for the day, we had two visitors from Eads come to look at the site. We all spent a little while talking about the site and the work.
By Gary Agranat
Bob was the first to leave, then Steve. Steve said he would check on Ed on the way home. Bill and I (Gary) convoyed out last.
While Bill and I were driving back to Colorado Springs, about an hour and a half into the trip back, an auto accident happened right in front of us, with a vehicle overturning.
The accident happened while we were driving westbound on Colorado Highway 94. It was early evening by then, about 5:30 pm, and the sun appeared above in the western sky. Bill and I had been talking on the VHF ham radio during our 2 1/2 hour drive back from the site. Bill was driving ahead of me.
A couple of miles before Rush, I saw three vehicles approaching from a long distance behind, moving faster than Bill and me, while we were going at about the speed limit. I mentioned the vehicles to Bill, and we stopped talking, anticipating they would choose to pass us soon. They did soon pass us, all three staying close to each other. We could see they were some sort of laborers, with equipment filling their vehicles and with ladders on top. The third vehicle passed us as we were going up a hill, with the solid yellow line on our side. Bill commented that car was taking risks, although they all were driving in a risky manner. There was no visibility over that hill. And furthermore we were driving into the sun. A couple of miles later we reached the town of Rush, where the speed limit lowers from 65 to 50 mph. As those three vehicles ahead approached the town, I suddenly saw the last one veer to the left side of the road, and then roll over, with its front turned facing the opposite direction. Bill and I both stopped, as did a driver heading in the oncoming direction who almost got hit. And several more cars stopped briefly. We saw one occupant lie in the grass, but he eventually got up.
Bill had a better view of the accident ahead of me. It looked to him like one of the three vehicles ahead suddenly slowed as he reached the town with the lower speed limit. The sun was right above and ahead of us, which created a greater visibility challenge. The sudden slowing apparently caught the last driver off guard, as he swerved to the right to avoid the vehicle ahead of him. But that put his right side of his car in the grass there, which caused a tire blowout and a swerve then to the left. And he overturned.
The volunteer fire department nearby responded relatively quickly. But we waited about 2 hours for a sheriff’s deputy to arrive, and then another hour for a State Patrol officer to arrive. The State Patrol was who we had to give our witness statements to. We didn’t finish with that until 8:30 pm, and I didn’t get home until 9:30.
The driver of the overturned vehicle eventually got up, but he refused medical help, although we wondered if he nonetheless might have been hurt.
Meanwhile the communities there are small, and everyone there knows everyone else. The other driver who stayed was a local woman school teacher. We chatted with her and also the volunteer firefighters, and with some of the neighbors who stopped to see if everyone was OK.
The State Patrol officer later explained to us that there were 6 accidents in the region called in within a period of 5 minutes, when our accident happened. One happened just about 9 miles further west from us on Highway 94, in the town of Yoder. That accident had injuries, and some of the firefighters who were with us then had to leave to respond to the other accident.
At a minimum, this is a reminder to take care to drive safely, especially with limiting conditions like the sun setting ahead.
Personnel present – Bill Miller, Ed Johnson, Steve Plock, Ed Corn, Myron Babcock, Bob Haggard, Glenn Davis, Phil Gage, Hans Gaensbauer, Rich Russel.
Rich Russel and Bob Haggard showed up Friday, joined later that day by Hans Gaensbauer. All three spent the night and Rich did radio astronomy observations. Bob Haggard finished the new front stairs for the communications trailer. Thanks Bob they look great! Everyone else came the next day. Glenn Davis and Phil Gage upgraded the software on pointing System 1, and Glenn installed the NTP server as well. Bill Miller and Ed Johnson were able to demonstrate go-to functionality on System 2 and the PID algorithm employed operated flawlessly. A milestone has been achieved and Ed plans to attempt sidereal tracking as his next step. Congratulations to all members of both pointing teams!
The fireproof door for the bunker hallway was cut to size by Steve Plock, Myron Babcock and Hans Gaensbauer. Ed Corn continued with electrical buildout in the bunker.
Again many thanks to all who participated and worked in the spirit of friendship and cooperation.
Bob Haggart N0CTV is working on building a new stairway and porch to the communications trailer at the radio telescope site. He started the work at home after taking measurements. Today he traveled to the site to continue the work. With him were his grandson Allen and Allen’s friend Ben. Bob writes:
“We arrived at 11 AM. Worked on the porch and covered the fan with 24″ X 24″ plywood. Ran out of time but did get the porch assembled and painted inside and out. The hand railing is only temporary and will finish next work day on the 17th.”
Bob’s work is replacing a small simple set of metal steps that has given us access to the communications trailer.
The new porch and stairway provide a great improvement.
Thanks to Bob for all this work, and for improving the access to the communications trailer.
Attendance: Gary Agranat, Ed Corn, Floyd Glick, Glenn Davis, Steve Plock, Rich Russel, Tony Bigbee, Ray Uberecken, Dave Molter, Jon Richardson, Bill Miller
Attending Remotely via TeamViewer: Skip Crilly, Dayton Jones, Jamie Riggs
Last Trips: Oct 19 Observation Trip. Oct 20 Work trip for ED. Steve, Hans, Gary, Paul
Next Trips to site: The regularly scheduled 3rd Saturday of the month, Saturday Nov 17th. Observation the night before on Nov 16th
DSES Technical and Operations Meeting- 2nd Monday of Every Month
DSES Science Meeting – 4th Monday of Every Month
Accuracy: The notes for this meeting may be out of order. This was done to group the discussion into subjects for better clarity and continuity, so they are not true chronological minutes. As always if I have misstated, omitted or misrepresented anyone please feel free to correct me WKM.
Agenda and Notes
Ray Uberecken has his mount ready to install a 12 ft dish with capability up thru the KU band. He needs to move the dish from the KCME radio station to his site in Payton. The dish F/D ratio is the same as the 60 ft Haswell dish, so the 12 ft dish could be used to prototype feeds and receivers for the Plishner site. Ray would like some volunteers from the DSES to help move it next Sunday the 28th at 10AM. (Note: Recent change of plans. Ray will hire a crane to pick the dish out of the KCME yard enclosure before disassembly. This is currently scheduled for 7 AM Saturday, November 10th.) He could use some volunteers, power drills with sockets and a trailer. KCME is at Fontanero and 1921 N. Weber in. Bill will send an EMAIL out to the group.
Once the dish is in place the first thing that Ray will install is a Dicke Switch.
Ray also wants to know if we want to use the 8 channel UHF remote at the site for reset and control of the systems. We have not been using it, but that is available and installed in the communications trailer rack and can be commanded remotely from Ray’s residence.
Ray has also started his optical observatory with 8 inch Celestron and a good refractor at his residence.
Dr. Rich Russel reviewed his new Radio Astronomy Guide Rev. 3.
The RA/Dec of many of the objects are from both celestial coordinate year 1950 epoch and year 2000 epoch, so needs updating.
The output of the SpectraCyber is in volts and a translation to Jansky is needed.
Rich and Gary observed a number of sources on the Oct. 19th observation trip.
Some source positions were very good. Others were not. This may indicate a pointing error or other system issue.
They were getting a lot of clear source signatures but don’t know what many of them were. Rich would like to do cross galactic scans while changing declination to map the whole area in the future.
Cassiopeia A, Cas-A, was thought to be seen, but at a relatively low amplitude. Cas-A, being a 2200 Jy source it should have been clearly seen but they weren’t sure they had it.
Sagittarius A was strong and had the instrument setup with too high of gain, resulting in scale saturation.
Special sources 1 and 2 were studied.
The special source 2, a contact binary star is getting close to a supernova event in a few years, and we want to baseline it and get ready to observe the supernova emission.
To find objects Gary used the tables in Rich’s observing guide and in the Data Book “Astrophysical Data: Planets and Stars” by Kenneth R. Lang.
The V notch object that Tony studied was not tried in Rich and Gary’s session.
Rich and Gary also did an experiment to measure the hydrogen (HI) Line Doppler shift and therefor the velocity along the galactic plane. They were able to get reasonable hydrogen measurements of the galaxy’s rotational velocity at multiple points from the center out to the radius of the sun.
Rich plotted these observations and got a curve that is in the ballpark but a little different than the published data on similar measurements. This is the first time that the Galactic angular velocity measurement has been attempted with the 60 ft. dish.
See Dr. Rich Russel’s attached Science Meeting presentation for more detail on the site trip and the observations mentioned above.
Tony Bigbee also went to the site for the observing session last week. Tony installed onto the system after Rich and Gary had finished. He did not get the expected results on the RASDR 4 receiver when attached to the 60 ft. dish over the weekend. He thought that the issue may be with the pointing accuracy of the System 1 controller. We used System 2 at the open house when Tony had very good results but did not get the same on this last weekend’s observation session using System 1. Tony looked for the V notch absorption object and is using a new code to calculate the source amplitude. He did not get good results on this and suspects pointing error.
He calculated the curves for the open house and last weekend’s observations showing time and discovered that these are different indicating that something is wrong between the two.
Tony did a Mollweide projection plot like the one below. In Tony’s plot the green line is the meridian, the blue line is the galactic plane. The black X is the position of the telescope. See Tony Bigbee’s actual plot when he posts or sends it out.
Rich suggests that anyone going down to observe should measure some of these same sources and get data to compare their results.
SkipCrilly says we have aligned NRAO 5690 at Greenbank and Haswell sites three times using the System 1 controller and it seems to be positioning correctly. Steve can do an additional observation next week, Tuesday and Wed and verify the alignment.
Another difference from the open house observation was that Steve Plock added the alternate cavity filter configuration.
As mentioned previously the coordinates of some of the sources are from celestial coordinate year 1950 epoch and year 2000 epoch so may be different positions now due to precession and galactic movement. A mathematical correction to the coordinates may be required to make an accurate set of coordinates for the current date. However, the small difference afforded by this is probably within the capture angle of the dish.
Glenn Davis says that his NTP time sever may be useful to improve the accuracy of the pointing systems.
Bill Miller said that the System 1 controller may still have a discontinuous elevation reading error. This was seen previously this summer and has not been fixed. This could contribute to a pointing error and inaccuracy on some coordinates.
Anyone going to do observations at the site should try to replicate the studies of the observation guide and use the Observation Checklist to make their session useful and comparative.
Currently the LMST is close to local time, and so one needs to consider this and observe in the evening instead of afternoon.
See the back of Rich Russel’s observing guide for dish rules and limits. An observation data sheet and suggestions are available in the back of the guide as well.
We need a list of some calibration sources to start all observing session with, to be sure that the pointing system is working properly and that it isn’t broken with new SW drops. Also, we hope the voltages we measure from calibration sources (with known Jansky levels), will enable us to derive the Janskies of other objects we wish to observe. Janskies are the measure of the flux density that the antenna receives.
Three papers have been accepted in the next SARA journal.
“The Deep Space Exploration Society 2018 Perseid Meteor Shower Open House”. By Bill Miller, Gary Agranat. Deep Space Exploration Society.
“SpectraCyber Neutral Hydrogen Measurements using the Deep Space Exploration Society 60 – foot Antenna System“. By Richard Russel D.Cs., Ae.E.; Gary Agranat. Deep Space Exploration Society.
“Dark HI Cloud Observation using the Deep Space Exploration Society Plishner 18 – Meter Dish with the RASDR4“. By Tony Bigbee, Richard Russel, Steve Plock. Deep Space Exploration Society.
Skip Crilly discussed his new 28 ft. antenna that has a 5 pixel or 5 separate antenna segment feed and is mounted on a cargo trailer but will be used mostly for SETI. The antenna may not be large enough to observe the strange signals we have seen. File size is one challenge since it is inversely proportional to the gain and noise ratio.
Meeting was adjourned after much secondary discussions not captured here.
Old 9/24/2018 Agenda and Notes from last science meeting:
Glenn Davis proposes a graphical user interface called Astro Guide that would allow better guiding and tracking of radio sources.
Rich’s presentation and overview of the radio astronomy guide
Started with Floyd’s list
Added the 1420 MHz sources from the book “Tools of Radio Astronomy” by K Rohlfs and T Wilson.
Added the hydrogen measurements from K5SO, Dr. Joe Martin who has provided signature images of the objects.
Gary, Jay Wilson, Rich and Steve all went to the site on 9/22 and did observations using the 60 foot dish.
Used Spectra Cyber
Used system 1 pointing
Used the new setup with the cavity filter
Limit switches are set at +/-15 ether way of north. CCW to 345. CW to 015.
Gary got great pictures of the event.
Need screen print capability to capture the Spectra Cyber parameters display.
The Spectra Cyber SW is easy to take the data and use it.
Need a Lap Top with a com 2 serial port to attach the spectra cyber. This is difficult because most of the Serial to USB port adapters don’t want to set for Com1 or Com2.
Need to do calibration sources before and after observation of an observed object and keep all settings on the Spectra Cyber the same.
From Tony, “To avoid problems of solar interference all observations were made between sunset and sunrise. Most scans were taken with the telescope on the meridian.” Galt and Kennedy, 1968, ‘Survey of Radio Sources Observed in the Continuum near 1420 MHz, Declinations —5° to +70°’ http://adsabs.harvard.edu/abs/1968AJ…..73..135G
Rich presented a number of plots from their observations. See Rich’s report.
The scan across the galaxy were at one RA. The radio hot area was offset from the optical.
The galactic rotation rate was also observed.
Got a lot of raw data, learned how to catalog it and analyze it.
The calibration sources did not show any signal above the noise.
Got good data for Sagittarius A, SAG A.
3 Papers have been submitted for the SARA Journal.
The Western SARA conference is in Boulder in March.
This is a summary of our activities at the Plishner radio telescope site during the third week of October 2018. Steve Plock, Ed Corn, and Gary Agranat contributed to this report.
Participants this weekend were Gary Agranat, Paul Berge, Tony Bigbee, Ed Corn, Hans Gaensbauer, Dave Molter, Steve Plock, and Rich Russel.
Our plan for the rest of the year is to work at the site during the third weekend of each month. The Friday evening is devoted to astronomical observing, and the rest of the weekend is then devoted primarily to infrastructure and equipment work.
60-foot Antenna Observing, by Gary Agranat, WA2JQZ
On Friday afternoon and evening Rich, Gary, and Paul did 1420 MHz neutral hydrogen observing with the 60-foot antenna. The primary observing goal was to take regular measurements of the hydrogen signal along the Milky Way galactic plane at 10 degree intervals, from the galactic center to about 110 degrees (a little more than the first quadrant). The Doppler shift of the hydrogen was measured at each 10 degree point. From that, Rich later used some basic geometry to derive a velocity and distance from the galactic center for each measurement. A second goal was to observe several known, strong galactic radio sources that could be used in the future for calibration of our observations, and also to see if we are capable of observing those sources in a consistent way (without unknown biases). A third goal was to observe additional galactic sources as targets of opportunity, to see how well we do, and to also see what problems we hit.
Galactic plane observing started at about 5 pm local time, when the galactic center in Sagitarius had risen high enough in the sky for us to observe. The galactic plane and most of the other observing were done with the 60 foot antenna pointed along the meridian (180 degrees azimuth to the south and zero degrees to the north), in order to eliminate the Earth’s rotational motion in the Doppler shift measurements. We observed until about 10:30 pm, when the team was then quite tired. To warm us up during the evening, we made a batch of hot apple cider.
Details of the observations and results were discussed at the science meeting on Monday October 22nd, and those will be covered in a separate post.
– Gary WA2JQZ
We’ll continue with the discussion of the weekend infrastructure work.
Saturday Infrastructure Work by Ed Corn, KC0TBE
Our first order of business was to re-service the toilet and spare in the outhouse. They now both have RV antifreeze for winter. Next installed was a portable heater for winter operations and I labeled all the breakers in the out house. I then labeled the doors with instructions for emergency exit and the safety pin for privacy at the main door.
With the help of Gary, Hans, and Paul we have the first 3 tower sections in place at the bunker, along with the first set of guy wires. [More about the tower below.]
-73’s Ed KC0TBE
DSES Site Work Report by Steve Plock KL7IZW, DSES President
Paul Berge worked on Friday, Saturday and Sunday. Because he travels from Lyons, Co. he prefers to maximize his efforts each visit. Also the weather window for the year is closing. I attempt to support his efforts as best as I can. Paul provided support for Rich Russel’s data acquisition which included galactic Doppler measurements. The team knocked off before midnight. Results have already been detailed in the Science meeting on 22nd of October.
On Saturday Ed installed a heater in the outhouse, winterized the RV toilets, and labeled the outhouse breakers.
During Saturday afternoon Hans, Ed, Paul, Steve and Gary all worked together to erect the new communications tower. The first set of guys were finished at 23 ft. by Ed Corn doing all the climbing. The majority of the rest of Saturday myself and Paul spent evaluating the elevation limit switch operation, including testing complete functionality with fault clearing via the built in override capability.
Later that day, Tony Bigbee showed up, and Paul and Steve supported subsequent hydrogen observations using the RASDR4 receiver.
The majority of Sunday was consumed by lubrication of the dish and adjustment of the azimuth drive chain. I also installed the conduit in the elevation bulkhead so that Bill Miller can complete his synchro wiring project.
Sunday Dave Molter worked into the night using the 500W floodlights and mixed over 1000lbs of concrete to try to prevent continued erosion in the ramp area. A big thanks to all who participated in this cooperative effort.
Participants: Steve Plock, Ed Corn, Rich Russel, Dave Molter, Gary Agranat.
Summary and photos by Gary Agranat.
We worked at the Plishner Radio Telescope site on Saturday August 25, 2018. One motivation was to proceed with needed infrastructure work before the cold of winter returns. Another motivation was to follow up on the observations we made during the Open House with the 60-foot antenna. In addition, the antenna tuner for the bunker ham radio station was still not running, and needed to be checked. Here is a summary of what we did, with some photos.
1. Ed and Steve replaced the outflow hose from the ramp sump with one more durable (including durable against mice). Ed tested that the outflow did drain away from the ramp area. We placed a new aluminum manhole cover on the sump access (vs the original steel one), fabricated by Steve.
2. Ed moved the Internet hotspot to the bunker. The hotspot was used by Gary while testing and operating the ham radio station.
3. Dave brought 20 x 60-pound bags of cement, and used all of them to continue to repair/rebuild the ramp retaining wall. He made considerable progress extending the base of the wall. The higher the base of the wall reaches up the ramp, the less rain sediment will clog the sump pump. Dave stayed until late in the evening, until around sunset. Gary stayed with him and gave some help.
4. Rich brought the SpectraCyber 1420 MHz Hydrogen Line Spectrometer, and used it to continue to test the functioning and ability of the SpectraCyber together with the System 1 pointing system on the 60-foot antenna. Rich later showed Gary how to steer the dish antenna, and how to measure and record neutral hydrogen data. By the end of the day we located and measured several radio sources in the Sagitarius region. And we made a systematic scan almost perpendicular to the Milky Way galactic plane, in order to measure neutral hydrogen while pointing away from and in the plane. A more detailed discussion follows later in this post.
5. Gary tested the setup of the newly installed auto tuner for the FT-897 in the bunker ham station. With some adjusting and checking of cable connections, the tuner was found to be functioning OK. Gary took the opportunity to operate K0PRT in the QSO Parties this weekend for Kansas, Ohio, Hawaii, and for the US & Canadian islands, making about 30 contacts, on SSB and CW, on 40, 20, and 15 meters. Signal reports were mostly good, which seemed to indicate the combined FT-897 + tuner system is working OK. Gary wrote some Guidance Notes for using the tuner, and left those next to the tuner.
6. We received 20 QSL cards in the mail from the Open House special event station. Myron passed them on through Ed to Gary. Gary responded to all of them, and sent in the mail our QSL card responses to all by Monday.
Next are some photos of our work. Then follows a more detailed discussion about the SpectraCyber observations with the 60-foot antenna.
SpectraCyber observations with the 60-foot antenna
Rich brought the SpectraCyber 1420 MHz Hydrogen Line Spectrometer, to follow up on the successful observations we started to make with the 60-foot antenna during our Open House 2 weeks before. We used the System 1 pointing system. I later joined him by mid afternoon, after I finished my other work, and this is a report of what we did.
We started by searching for several sources with flux density values higher than 200 Janskies. However, at first no sources were found. The plane of the Milky Way was at that time very low along the southern horizon. There were few strong sources on our list available to look for at that time.
A little later, we just about ran into the Milky Way without looking for it, when the galactic plane rose higher. The signal trace of the SpectraCyber indicated the change: pointed away from the galactic plane, the signal trace stayed near about 3 volts, varying probably with noise, but not by more than a volt. Once pointing at the galactic plane, the voltage trace increased from about 5 to 7 volts (up to about 4 volts above the noise floor). The signal consistently showed a peak at about the center of the trace, at about the frequency of neutral hydrogen. We have not calibrated the SpectraCyber, and so we don’t exactly what frequency we were peaking. (The actual spectral line frequency is 1420.40575 MHz. And we may be seeing some doppler shift in our measurement.)
We then looked for several strong sources in the Sagitarius region, which by then had risen. We successfully found several, including:
Sagitarius A, the center of our Milky Way galaxy. The radio emission is thought to be from the secondary effects of a black hole there.
CTB 37, a supernova remnant about 20,000 light years away (see https://www.nasa.gov/mission_pages/chandra/ctb-37a.html.) Our signal trace showed three peaks through most of our scans. Our interpretation is that the central peak is the original supernova remnant. The other peaks would be the doppler-shifted material outflowing away and towards us, following the supernova explosion.
The Sagitarius Star Cloud Messier 24, with a colder hydrogen cloud closer along the line of sight that absorbs some of the M24 hydrogen signal. This is the radio source Tony Bigbee pointed to during our Open House 2 weeks earlier. The signal trace has a distinctive dip, which had been identified in data from the Parkes Observatory in Australia. And as Tony has discussed, was used in the past by the RASDR2 team as an engineering detection test. The dip in signal is interpreted as a hydrogen cloud along the line of sight that is colder than the background source. It absorbs the background signal and then reradiates it out, but in all directions, hence the net signal to us is reduced. We used the RA & Dec location coordinates recorded during the Open House. We found the source again without difficulty.
We used the System 1 computer display to read the angles our 60-foot antenna was pointed to. The display showed coordinates in both azimuth & elevation (Earth ground reference), and Right Ascension & Declination (celestial sky coordinate reference). We turned the antenna with the manual steering controls. At this time we do not have automatic tracking ability. But we were able to reasonably stay on our targets with continual manual adjustments. What we more often did was we found our source, then allowed the antenna to scan at the set elevation as the Earth rotated, and as a result get a short scan along a line of Declination. We then moved the elevation up and down slightly, to see differences in the scans a little north and south. We used this technique also to hone in on targets.
We then manually scanned across the Milky Way galactic plane, to obtain a slice from 16 to 20 hours Right Ascension, along the declination of -05 degrees. We stopped at intervals of 30 minutes Right Ascension (e.g., 17h 00 min, 17h 30 min, 18h 00 min, …), to let the SpectraCyber take full scans.
Our scan cut a steep acute angle through the width of the galactic plane, going across the constellations of Ophiuchus, the north edge of Scutum, and the southern part of Aquila. We therefore started and ended at angles pointed “above” and “below” from the galactic plane, and scanned across the galactic plane in between.
Since we were pointing to the southeast (and not due south), if we moved azimuth while maintaining elevation, the declination still changed. And so to keep on the -05 degree declination line, we had to adjust azimuth and elevation together.
DSES Science Meeting August 27, 2018 Follow Up
On the following Monday we had our monthly DSES Science Meeting at the home of Rich Russel.
At the meeting we discussed the observations we made with the 60-foot antenna two days earlier.
Tony Bigbee then also presented deeper details about his RASDR4 (Radio Astronomy Software Defined Radio). And he gave us more background about the earlier RASDR2 observations of Messier 24, with the dip in frequency. And he showed how he researched the earlier Parkes observatory data to find useable results and plots for us to compare to.