Looks like a break in the weather. Shifted the 2600 from the 14” to the 102mm (with LP filter), and was out at 17:00 starting the focus/flats/dark flats routine. Focus was done using a Bahtinov mask. Several objectives tonight including obtaining images so that the refractor performance can be compared to the same objects run last year with the Hyperstar, viewing the ISS and then capture of comet C/2002 E3 ZTF. The sky’s “winter transparent” with a 10mph breeze and temperature in the low 40s.
M33 I initially started imaging with 1 minute exposure to avoid burning out the core, but gave up on that after a bit and shifted to 3 minutes.
- M33 stretched arcsinh s.jpg (2.38 MiB) Viewed 965 times
18:03 – 22:01 hrs EST, 19 Jan 2023
80 X 3 min, unbinned, 200 gain, -20° cooling, 1 Hz guiding
Explore Scientific 102mm triplet with Optolong LP-P filter and ASI 2600MC-P camera
For comparison, here’s the 1 Nov 2021 Hyperstar image:
- M33 8x11.jpg (1.58 MiB) Viewed 965 times
The hour and 33 minute Hyperstar image shows a tad more detail that the 4-hour refractor image. Very much brighter.
The ISS had a decent pass: 36° above the NW horizon. Parked myself in a chair in a dark section of the back yard at 18:45. Always amazed with an ISS pass and this one didn’t disappoint. -2.5 magnitude.
Upon completion of M33 the night is still perfect for stargazing. The wind’s died completely.
All the wonders of the winter sky are there before me, but the 2nd object must be quick as I’d like to catch some sleep before climbing out of bed in the wee hours for the comet. M45 looks like it could be a quickie as the previous Hyperstar image was only 19 X 1 minute.
Messier 45 – the Pleiades
- M45 s.jpg (1.13 MiB) Viewed 965 times
13 X 3 min, unbinned, 200 gain, -20° cooling, 1 Hz guiding
Explore Scientific 102mm triplet with Optolong LP-P filter and ASI 2600MC-P camera
Again, I stacked and ran the initial arcsinh stretch in IP and did the rest of the processing in PS. This is noticeably better than the 2 Jan 2021 Hyperstar image run 19 X 1 min, -20C 100 gain:
- M45 annotated.jpg (4.17 MiB) Viewed 965 times
Friday, 20 Jan 2023
Comet C/2022 E3 ZTF is only .5 AU (48 million miles) from Earth and is reportedly very bright. With an apparent motion of 5”/minute I’m not quite sure as to what to use as exposure times. First try is 49 X 1 minute (03:38 – 04:27 hrs) The tail’s not as bright as anticipated, so 2nd try is 14 X 3 minutes (04:34 – 05:13 hrs). Let’s see how that went….
- Comet 2022 E3 ZTF s.jpg (1.26 MiB) Viewed 965 times
Conclusions & lessons learned:
The M33 images were brighter on the right hand side of the frames, and I’ve previously observed this to be a problem. While it’s possible that the computer screens were shining on the left hand side of the dome shutter it’s also possible that there’s a small light leak through the ASI filter drawer. The filter area was covered for subsequent imaging and there was no problem with M45 or with the comet.
While the Triangulum was brighter in the Hyperstar image there’s sharper detail and better color in the new refractor image.
M45 is significantly improved over the old Hyperstar version. Exposure was 39 minutes rather than 19 minutes. Vastly different scopes but improved processing skills?
Comet ZTF was discovered last March by the Zwicky Transient Facility. According to NASA, ZTF has a greenish, coma, short broad dust tail, and long faint ion tail. The greenish color associated with a molecule made from two carbon atoms bonded together, called dicarbon. Dicarbon molecules emit green light as sunlight decays them.
The very noisy live stacked frames in Sharpcap showed traces of both tails all the way up to the NW corner of the image. Had the same noise problem when stretching the image in post processing so the final image here is really a compromise.. I’ve used it before, but figuring out the DSS stacking software was a challenge this time around. Now that I’ve got it in hand I’ll be trying for the comet again only with increased exposure. It’ll be an evening object by next week and that’ll make things easier too.
