Archive for July, 2012

Unbelievably there were a couple of hours of clear sky (and no Moon) last night 🙂  As both the mini-WASP and the new Hyperstar III setup need tuning it was a hard choice of which one to work on.  Expecting to finish the Hyperstar III and maybe even grab an image too – I went for the Hyperstar.  Needed to refocus-train the system as there is a new camera on board, and then it was the old collimation routine.  Got to a point of pretty good collimation but poor star shapes around the edges.  Think this needs another bit of optical hardware to get rid of that – so next outing I suppose.  Three hours work done before the clouds rolled in – can’t complain – better than nothing.

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If you’re into Science Fiction I can highly recommend “Slabscape: Reset” – the best thing I’ve picked (well Kindled anyway) since William Gibson’s Neuromancer – and that’s going back a LONG time 🙂

 

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Spica

Star name:                                          Spica

Other names:                                      Alpha Virginis, Azimech, Alaraph, Dana

Constellation:                                     Virgo

Other ID:                                             67 Virginis, HR5056, HD116658, SAO157923, HIP65474

Magnitude:                                         +1.04

Absolute magnitude:                          -3.55

Luminosity, Sun = 1:                          12,100

R.A. 2000:                                          13hr 25min 11.5793sec

Dec 2000:                                           -11deg 09min 40.759sec

Spectral type:                                     B1 III-IV/B2 V (Beta Cephei type variable, rotating ellipsoid)

B – V colour index                              -0.24

Temperature:                                      22.400 K

Mass, solar masses:                            10.25 +/- 0.68

Radius, solar radii:                             7.4 +/- 0.57

Distance in light-years:                      260 +/- 20

 

Spica is the brightest very blue star in the night sky, the brightest star in Virgo, and the 15th brightest star in the whole (north and south) sky.  Spica is a close binary with an orbital period of about 4 days.  Spica is a Beta Cephei type variable which has a brightness variability over a 0.1738 day period, in addition, due to the presence of its companion star, Spica is also a rotating ellipsoidal variable leading to an apparent magnitude change of 0.03 over the binary orbital period. Note that this is not an eclipsing binary, but an effect of gravitational distortion due to the close companion star.  As Spica is close to the ecliptic it can be occulted by the Moon and sometimes by the planets as well.  From my 51 degree north location Spica can be seen close to my southern horizon during the spring.  In 2012 as Spica crossed my southern horizon it was accompanied by Saturn which travelled almost directly above it creating a nice photo-opportunity for a wide field setup.

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Well I don’t think there is going to be much let up in the rain for a good few months now – I have just received a new camera for the Hyperstar III.  For quite a while now I have used the faithful Starlight Xpress M25C one-shot colour CCD on the HSIII – 6-Megapixels and 2.85 arc seconds per pixel sampling – it has performed flawlessly and provided some superb images.  BUT – there’s always developmental improvements at Starlight Xpress and as I now have quite a bit of experience using the new M26C cameras on the mini-WASP array, it became clear that this should be the new camera for the HSIII.  So I’ve leapt up from 6-Megapixels to 10-Megapixels and my sampling has gone up from 2.85 arc seconds per pixel to 2.1 arc seconds per pixel.  The Hyperstar III and the M26C are going to be a formidable combination.  Last night I managed to get all the software working with the new camera and the next job is to focus train the new system using Starizona’s Microfocuser system and FocusMax.  With the system focus trained for the new camera it’s then a matter of flattening and collimating the camera using CCDInspector (and FocusMax) – and then I’ll be all set for imaging again.  Really looking forward to putting the new combo through its paces 🙂  Guess I also now need to create a new Category for this web site – Hyperstar III and M26C CCD images.

 

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Whereas there are lots of very red stars in the night sky (not many bright ones though) there are fewer very blue stars, that is stars with a big negative B-V index.  The brightest very blue star in the night sky happens to be Spica, which I was only really aware of this year, very low down on my southern horizon, travelling along with Saturn, during this Spring.  As I am interested in imaging the brightest very red and very blue stars in the night sky I imaged Spica with the Hyperstar III and the M25C camera, but being bright meant that I got an enormous unwanted lens flare from the Hyperstar III.  I can’t deal with bad lens flares in the processing, so Noel Carboni came to the rescue and processed this one for me.  Great job Noel!!

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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.

 

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UU Aurigae

Star name:                                           UU Aurigae

Other names:

Constellation:                                      Auriga

Other ID:                                             SAO 59280, HD 46687, HIP 31579, HR 2405, BD+38 1539

Magnitude:                                          5.446

Absolute magnitude:                            -3.1 +/- 1.1

Luminosity, Sun = 1:                           1400 +/- 1400

R.A. 2000:                                          06hr 36min 32.8364sec

Dec 2000:                                           +38deg 26min 43.8sec

Spectral type:                                      C5II semiregular variable

Temperature:                                       3,450 K

Mass, solar masses:

Radius, solar radii:

Distance in light-years:                       1,630 +/- 820

 

UU Aurigae is a binary Carbon star in the constellation Auriga.  Period of variation 441 days.

 

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RS Cygni

Star name:                                           RS Cygni

Other names:

Constellation:                                      Cygnus

Other ID:                                             SAO 69636, HIP 99653, PPM 84477, HD 192443, B+38 3957

Magnitude:                                          7.1 to 8.5

Absolute magnitude:                            -0.77
+/- 0.92

Luminosity, Sun = 1:                           170 +/- 140

R.A. 2000:                                          20hr 13min 23.662sec

Dec 2000:                                           38deg 43min 44.47sec

Spectral type:                                      C5II

Temperature:

Mass, solar masses:

Radius, solar radii:

Distance in light-years:                       1550 +/- 650

 

This Carbon star lies very close to the Crescent nebula (NGC6888, an emission nebula formed from the Wolf-Rayet star HD 192163) in the constellation Cygnus.  The mean period of the variability of RS Cygni is 434.1 days.

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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.

 

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La Superba

Star name:                                          La Superba

Other names:                                      Y Canum Venaticorum

Constellation:                                     Canes Venatici

Other ID:                                             SAO 44317, HIP 62223, HD110914, HR4846, GC17342

Magnitude:                                         4.8 to 6.3 (variable over 160 days)

Absolute magnitude:                          -7.63

Luminosity, Sun = 1:                          4,400

R.A. 2000:                                          12hr 45min 07.827sec

Dec 2000:                                           +45deg 26min 24.922sec

Spectral type:                                     C7 (CN5) supergiant

Temperature:                                      2,200 (2,800) K

Mass, solar masses:                            3

Radius, solar radii:                             215

Distance in light-years:                      711 +/- 113

 

La Superba in the constellation Canes Venaticorum is one of the brightest Carbon stars in the sky but it is not a naked-eye object as most of its output is in the infrared part of the spectrum.  It was named “La Superba” by Father Angelo Secchi who was amazed at the beauty of its spectrum, and as you can see in the accompanying (north up) image, it is a strikingly brilliant red star.  La Superba is a very special type of Carbon star, it is in fact the brightest “J-star” in the sky, where a J-star is a very rare group of Carbon stars that has an abundance of Carbon-13 (heavy Carbon).  At between 2,200 and 2,800 K La Superba is one of the coolest true stars known.  In the accompanying image, which was the Astronomy Picture of the Day (APOD) for December 18th 2008, we once again see the obligatory brilliant blue star (SAO 44292) lying at the 1 O’clock position from La Superba.  There are also a number of faint background galaxies in this image, the most obvious lying at the 7 O’clock position which is magnitude 15.7 PGC 43044.

 

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