WZ Cassiopeiae

Star name:                                           WZ Cassiopeiae

Other names:

Constellation:                                      Cassiopeia

Other ID:                                             SAO 21002, HIP 99, HD 224855, B+59 2810, PPM 11856

Magnitude:                                          6.772 to 7.215

Absolute magnitude:                            -2.7 +/- 1.0

Luminosity, Sun = 1:                           980 +/- 910

R.A. 2000:                                          00hr 01min 15.855sec

Dec 2000:                                           +60deg 21min 19.016sec

Spectral type:                                      C5p

Temperature:                                       3,450 K

Mass, solar masses:

Radius, solar radii:

Distance in light-years:                       2900 +/- 1300

WZ Cassiopeiae is a Carbon star in the constellation Cassiopeia.

SAO 12874 and SAO 12870

Star name:

Other names:

Constellation:                                      Camelopardalis

Other ID:                                             SAO 12874, HIP 17296, HD 22649, B+62 597, PPM 14446

Magnitude:                                          5.05

Absolute magnitude:

Luminosity, Sun = 1:

R.A. 2000:                                          03hr 42min 09.325sec

Dec 2000:                                           +63deg 13min 00.501sec

Spectral type:                                      S5.3 SB

Temperature:

Mass, solar masses:

Radius, solar radii:

Distance in light-years:                       520.19

Star name:                                           U Camelopardalis

Other names:

Constellation:                                      Camelopardalis

Other ID:                                             SAO 12870, HIP 17257, HD 22611, B+62 596

Magnitude:                                          6.99 (6.9 – 7.6)

Absolute magnitude:

Luminosity, Sun = 1:

R.A. 2000:                                          03hr 41min 48.172sec

Dec 2000:                                           +62deg 38min 54.382sec

Spectral type:                                      C3
- C6(N5)  Carbon star

Temperature:

Mass, solar masses:

Radius, solar radii:

Distance in light-years:

SAO 12874 and SAO 12870 are a pair of red stars lying just to the right of the famous “Kemble’s Cascade” asterism.  SAO 12874 has B-V 1.97 and SAO 12870 or U Camelopardalis has B-V 4.91 so it is a very red Carbon star.

Mu Cephei

Name:                                                  The Garnet star

Other names:                                      Herschel’s Garnet star

Constellation:                                     Cepheus

Other ID:                                             Erakis, HD206936, HR8316, SAO33693, HIP107259

Magnitude:                                         4.08 (variable)

Absolute magnitude:                          -7.63

Luminosity, Sun = 1:                          370,000 (possibly as much as 600,000, uncertain figure)

R.A. 2000:                                          21hr 43min 30.4609sec

Dec 2000:                                           +58deg 46min 48.166sec

Spectral type:                                     M2Ia supergiant

Temperature:                                      3,690 +/- 50 K

Mass, solar masses:                            15

Radius, solar radii:                             1650

Distance in light-years:                      2,400 (Kaler – uncertain)

This is the reddest star in the entire night sky and at magnitude 4.08 it is naked-eye from reasonably dark sites too.   The incredible output power of the Garnet Star (check that Luminosity figure!) makes it one of the most luminous stars in the whole of our Milky Way.  Mu Cephei varies by almost a full magnitude with a semiregular period between 800 and 1,000 days. In the accompanying image, north is up and Mu Cephei is the bright star towards top left.  As you can see it sits on the outer edge of the massive IC1396 emission nebula.  At bottom far right you can see the famous “Elephant’s Trunk” nebula.  The constellation Cepheus is a very rich region for imaging interesting deep-sky objects.

Last night was the most amazing beautiful clear night – and the Moon wasn’t too intrusive either (which is unusual on a clear night).  After a little extra “tuning” I set the two mini-WASP cameras off imaging a region around M57 in Lyra and I set the Hyperstar III off taking long subs on M92.  The data from all 3 cameras was shipped up to the monitors in the study so I could see what was going on outside whilst listening to CDs in the comfort of my chair indoors.  Top left screen is camera 1 on the mini-WASP, top right screen is canera 2 on the mini-WASP, bottom left screen is the Hyperstar III, and bottom right screen is the Internet.  It really doesn’t get any better than this

Noel Carboni compared two sets of M101 data taken using two different imaging systems (but the same imaging camera) at the New Forest Observatory.

The top image shows in excess of 5-hours (total) data, probably nearer 8-hours, taken using the Sky 90 and M26C 6-Megapixel one-shot colour CCD in 2007.  The lower image shows the recent 2012 data taken using the Hyperstar III with the same imaging camera with exactly 5-hours of total exposure time but this system is at f#2.  Now, theoretically (and practically it seems) an f#2 system is 5 times faster than an f#4.5 system, so 5-hours worth of Hyperstar III data should translate to 25-hours worth of Sky 90 data, which seems about right.  Note the faint outer arms visible in the Hyperstar data that are totally missing from the Sky 90 data.  Also note the far greater number of stars apparent in the Hyperstar data compared to the Sky 90 data.

What does all this have to say about the mini-WASP concept?  Well the Sky 90/M25C (or M26C) combination gives twice the field of view of the HSIII/M25C combo.  As the HSIII is 5x faster than the Sky 90 then I would need to take the equivalent of 5 frames of HSIII data using the Sky 90 in the same time which is 2 and a half Sky 90s, when I have two currently configured.  So 2 Sky 90s doesn’t quite break-even compared to one Hyperstar III, if I get 3 Sky 90s imaging at the same time on the mini-WASP array then I am slightly winning over one Hyperstar III.  The only other thing in favour of the mini-WASP array is that I can fit a filter-wheel to the Sky 90s (not possible with the Hyperstar) so I can grab narrowband data easily with the mini-WASP array as well.  Lastly, the Sky 90s do seem to offer slightly better contrast than the C11/Hyperstar, it’s only a small improvement – but it is there.  The Hyperstar III has higher sampling (better resolution).

So when you add it all up, is the mini-WASP array as I have configured it a very good idea?  Probably not.  A better approach would be to use 4 cheap large aperture refractors each with a full-frame mono camera and IDAS, H-alpha, OIII, SII filters (one for each scope) – as you are narrowband imaging you aren’t too worried about superb chromatic aberration compensation and the refractors don’t need to be top of the range.  You would then image THE SAME object with all 4 scopes and get all your data for processing down in one go.

Noel Carboni added that recent Hyperstar III data to our earlier Sky 90/M25C one-shot colour and narrowband data to give this stunning result!

This is last night’s Sky-Watcher data (2-hours) composited with the earlier Sky 90 data (11 and a half hours) – so 13 and a half hours total into this one so far

In order to see all the galaxies and the asteroids more easily – here’s the image below in negative B&W   Enjoy!

A slightly more careful processing of the earlier data.  At least 4 asteroids in there and North is to the right

I found a couple more frames lurking in the archive, as well as realising that I’d lost a few with M89, M90, M91   I will have to retake those again.  This massive field of view is precisely what I built the mini-WASP array for and hopefully I will eventually get round to imaging this galaxy field, in anger, with an instrument actually made for the job.  The way things are going I doubt whether I will be ready in time for this spring, but I will give it a good try