Observations - 16/02/21

Good evening, everyone on IFAS.

Early on Pancake Tuesday evening between 5 and 7 pm I was out observing with my William Optics 158 mm F/7 apochromatic refractor. Sunset had occurred at 5.38 pm. The temperature was 6˚ C. There was a 20 km/h wind which I felt kept the dew away. It had become cloudy by 8 pm.

1.There was a 5 day old crescent Moon which was of -8.6 magnitude. Its distance was almost exactly 400,000 kms from us. It was 23.3% illuminated and its angular diameter was 29.8’. As Mare Crisium was very prominent, I got straight to work on that area. The 126 km crater Cleomedes is immediately north of Mare Crisium. But I was completely amazed to see a fairly straight and very faint white line west of the crater Cleomedes E (21 km). Checking with Antonin Rukl’s Atlas of the Moon on map 26 it seems I have made my very first observation of Rima Cleomedes. This rille is 30 kms long and is north of Cleomedes’ central peak. I observed the satellite craters Cleomedes J (10 km) and B (11 km) also. Cleomedes E and A (12km) looked very good too. Back in Mare Crisium, the craters Swift (11 km), Pierce (18.5 km), flooded Yerkes (36 km), Picard (23 km) were easy to see. However a very small 3 km crater called Curtis I did notice for the first time. It had a nice slightly conspicuous rim and a noticeable floor. Further north I did see Atlas (87 km) which was good to see. Although there was no sign of its central rilles. The 69 km crater Hercules’ centre was in completely darkness. But its entire outer rim was fully visible. Stunning!

As the sky had become considerably darker by this time, I headed over to Taurus the Bull. And I do have a carbon star for you all. However I start with these 3 doubles. The figures I use can be found on www.stelledoppie.it which I completely trust and it is always updated every January. Why not check it out? It’s completely free!

2. AG 68 is a true binary which I have never observed before. Magnitudes: A = 6.8. B = 9.9. Sep = 16.9". PA = 249 degrees. I observed a very pleasant split at 40X and 112X. I was content not to see any colours in either star - it was about 30 minutes after sunset after all. AG stands for Astronomische Gesellschaft.

3. 30 Tauri (STF 452) I haven't observed for many a long year. I had it ticked off in my Robert Burnham Celestial Handbook Volume 3. It is an uncertain double which means professional astronomers are not sure if it is a true or optical system. Magnitudes: A = 5.1. B = 9.8. Sep = 9.2". PA = 60 degrees. These 2 white stars are a great delight at 112X. However I then discovered I had an even more pleasant and tighter split at a mere 40X.

4. Very close by is an uncertain double which I was looking forward to observe. A 832 has magnitudes: A = 10. B = 10.4. Sep = 1.7". PA = 114 degrees. I had no split at 112X. But at 140X I could see a tiny black gap between the 2 faint stars. Success! And it looked superb at 167X and easy at 225X. Robert Grant Aitken (1864-1951) appears to be its discoverer as far back as 1904.

5. And so I share my new carbon star which is also in Taurus. TYC 660 420 is also called DO 616 on Simbad. This C spectral class star is positioned in western Taurus near the double star AG 68 and I did print a detailed map from my Guide 9.1 DVD before I observed it and is the very first carbon star I came across from the western side of Taurus in the lowest RA. On this map I had to observe 4 stars which are arranged in slightly curved line. These stars and their magnitudes were TYC 660 410 (11.6), TYC 660 579 (11. and TYC 660 519 (10.5). The target star is seriously faint at magnitude 11.3. But it presented itself at a very reasonable 112X between the first 2 stars above. As I increased to 225X the star did have a fairly decent orange colour. I was overjoyed when I had it all figured out. DO 616 or TYC 660 420 is my 96th observed carbon star. Other carbon stars I have observed in the past in Taurus were: TT, TU and Y Tauri. So it is nice to add a 4th. I do promise the next carbon in Taurus will be a brighter one.

6. Finally imagine my immense shock as I was observing the very faint carbon star TYC 660 420 at a magnification of 167X when suddenly a very brilliant bright white light shot through my 29 arc minute field of view! I looked up straight away and I saw a quite a bright man-made satellite heading from Taurus into Perseus. When I came inside I discovered on www.heavens-above.com who the culprit was. It was the Italian Sky Med 2 satellite which had, at the time, a magnitude of +3.6. But I was most pleased to have realised what it was all the same. I see it was originally launched in December 2004.

Clear skies to you all from Aubrey.

Hi Aubrey, 

Very many thanks for your brilliant report from Tuesday night. It seems to have been a great one!

And a BIG congratulations on observing your 96th Carbon star, particularly considering you had to go to 225X to really pull out the it's orange hue.

I thoroughly enjoyed reading your lunar report because I was hoping to get a close up look at myself, but that wasn't to be. Rima Cleomedes sounds delightful, and your description of Hercules is fantastic... It must have looked pretty spectacular. 

Also nice piece of investigation work with that satellite...I must try to identify one sometime. After all there are plenty of them for us to spot

Clear skies to you, 

Darren. 

It is amazing how many satellites interrupt a telescopic session Aubrey, even with narrower fields of view. The whole sky is pretty much alive with them.

Finbarr.