StarLock Guiding Improved, Sombrero Galaxy, M87 Jet
Posted: 4 May 2016
Just before going out to the observatory a local Antelope Squirrel family came out for stroll. This was the first time the young ones were let out.
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Open: Tuesday, 3 May 2016, 1840 MST
Dome onto PZT. Used the Wireless AutoStar II handcontroller for this session as I wanted to test the Wi-Fi connection to the telescope.
1909 MST: Jupiter was visible to the naked eye. 1911 MST: sunset. LX600 ON, StarLock OFF. 1913 MST: viewed Jupiter, 102X. Nice view; the four Galilean Moons were visible. Switched to 443X (5.5mm eyepiece). Fairly good view. The disk of the moon Ganymede was visible.
I then did comparison tests of three star diagonals: Meade 2", Meade 1.25" (that came with the LX600), and OPT 2". The view using the Meade 2" diagonal was not as sharp as the view using the Meade 1.25". The view with the OPT 2" diagonal was almost as good as the Meade 1.25". I have begun to wonder if I need a 2" star diagonal that is designed for the LX600 f/8 ACF optics. I will continue using the OPT 2" diagonal.
1950 MST: began Wi-Fi tests using the GC Wi-Fi Adapter. It worked great with the SkySafari 5 Pro and ScopeBoss iOS apps. Actually, it was surprising that it worked. When I first set up the LX600 in the observatory Wi-Fi did not work when I used the Wireless AutoStar II handcontroller. The Wi-Fi adapter had been on the tripod. When the telescope was mounted on the pier I had to relocate the adapter, so maybe whatever interference that had been caused by the tripod has been eliminated.
2007 MST: began setting up for D7200 DSLR prime focus imaging of Jupiter. Used the 2" 2X PowerMate + 1.25" 2X Barlow Lens. Did several HD video recordings of Jupiter, 1.3X crop factor, 60 fps, White Balance Auto, at various exposure settings. This is a stack of 939 video frames, 1/125sec, ISO 6400, downscaled about 30%:
2032 MST: removed the camera and slewed to the star Denebola. StarLock ON. After the poor guiding results on the previous session I wanted to try to improve the StarLock guiding. I monitored the StarLock guiding status display on the AutoStar for a few minutes. Most times the values were "0.2 0.3" or less (good). But every few seconds the numbers would jump to 2.0 or greater (not good), before coming back down. I had manually set the RA Guide Rate to 10% and the Dec Guide Rate to 10%. Slewed to the star Spica and did the StarLock Automatic Rate Calibration (ARC), which did not complete on the previous session. This time it worked correctly and completed in 11 minutes. It reported R23 D52. That seemed a little high, especially the DEC guide rate. While the ARC was in progress I rechecked the LX600 manual and discovered I had made a mistake when I redid the RA PEC training on the previous session. I had set the RA Guide Rate to 10%; it should have been 33% for RA PEC training. When the ARC was completed I slewed to the star Arcturus to redo the RA PEC training. 2100 MST: erased the old (bad) PEC data and started the new RA PEC training. 2216 MST: the initial and two training updates were completed. Slewed to Spica and monitored the StarLock status with the RA Guide Rate at 33%. It varied from 0.2 to 2. Changed the RA Guide Rate to 10%; now the numbers were below 2, which should be good for StarLock guiding.
2222 MST: began setting up for prime focus imaging. Did a focus test image of Spica using the Astrozap mask. Then imaged M104 (Sombrero Galaxy) at ISO 4000, White Balance 4000K, using various exposure lengths. Some trailing was still evident but the StarLock guiding was way better than on the previous session. This is a 3 minute exposure, cropped from the full-frame image:
Slewed to Omega Centauri (globular cluster), which was very low in the southern sky. The StarLock had a problem locking on to a guide star, but finally did. I attempted an image but it was not good. Will try again on the next session.
I then slewed to M87 to image the jet coming from the galaxy's black hole. I had successfully imaged it with my 8" LX200-ACF and wanted to try it with the 12" LX600. This is a cropped 1 minute, ISO 2500, White Balance 4000K, exposure:
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While I was doing the imaging of these Deep Sky Objects (DSO) I noticed that StarLock guiding was better when I set the AutoStar slewing rate to "Guide". That surprised me as I thought that setting only applied to slewing when using the AutoStar handcontroller.
2306 MST: completed imaging. StarLock OFF.
2316 MST: viewed Mars with the Baader 8-24mm Zoom Eyepiece. The best view was at 203X (12mm). Mars was very bright but some surface details were visible. Will definitely need to use some filter when viewing Mars higher in the sky and closer to the Earth as Mars comes to opposition later this month. Then viewed Saturn. Pretty view at 203X. Both planets were still low in the southeastern sky so viewing was not the best.
Close: Tuesday, 3 May 2016, 2333 MST
Session Length: 4h 53m|
Information on the upcoming opposition of Mars is available at the Arkansas Sky Observatories web site.
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