I attach an STX file. The list contains the stars of special spectral characteristics that Angelo Secchi submitted to the French Academie des Sciences in 1868.
Secchi investigated the stars contained in Schjellerup's Catalogue of Red Stars and found these 16 stars (a 17th star is not clearly identified) to be markedly different from all others. Today we know them as carbon stars.
The rating is based on Secchi's aesthetic evaluation.
This has got me interested and the file shows 12 are visible in the Southern Hemisphere. It is really great to see people sharing their STX files, so thanks Chamukuy, I appreciate your file.
If you're interested in carbon stars, the Skyhound website has an Astronomy League .stx file with 100 carbon stars in it. 24 of them have negative declinations. R Lep is included. The list is called 'AL Carbon Star'. Of course, it doesn't have the historical significance of Secchi's list.
I remember observing R Lep. It's so red that it can't be seen with averted vision, the eye's rod sensors aren't sensitive to the red light. You have to be looking directly at it.
Thanks for providing the observing list, Chamukuy.
Hi Phil
Thanks for the tip. I am checking these out to see what is different about them as I had not heard about Carbon stars before. I will start with R Lep and see if my eyesight is still good enough, then start looking for the other ones. I have 2 goto scopes, but like the challenge of finding a target without it.
I will let you know what I find
At 5.75 R Lep has one of the highest B-V values going. It's incredibly red. ST4v says it's currently 8.6 magnitude, so it should be easy to detect. You can use the Database Power Search to look for stars with high B-V values that are bright enough for your scope. I just did a DBPS search for red stars with B-V>3, brighter than 15th magnitude. ST4v returned 1761 objects. That should keep you busy .
R Lep was at the top of the list. DY Cru was next at B-V=5.56. You can also limit the search by date or observing location. The DBPS is a very powerful observing tool.
I had to google J stars I think I need to read more...
I am keen to try these out once the cloud goes, but we are in the midst of a storm so may take a few days.
You have not wasted your time uploading them, they are both in my list now thank you.
Yes, the B-V color index is the difference between the blue (B) & visual (V) magnitude of objects measured through those filters. Red objects have very positive B-V values & blue objects have negative values. Other colors fall in between. I think the ST4v Help has an explanation. 'Color' is the parameter that you want to set for the Color Index.
Here's the part of the DBPS dialog that lets you select the Color Index range that you want. If you have the Tool Tips turned on & hover the cursor over this area, you'll get more info. [attachment=2305]
.