Finally got some colour for my NGC104 image, with NGC121 getting a look in as well. Two globs in two galaxies! Not very much data or not as much as I wanted although for now it will have to do. Still struggling with focus, will try to get out under the moon and nail the Temp Compensation and see how that goes.
Details
Telescope: William Optics FLT132
Guide Scope: QHY OAG
Camera: QHY9 Mono @ -20c
Filter Wheel: QHY 7 position Ultra Slim
Filters: QHY 36mm unmounted L R G B HA OIII SII
Guide Camera: QHY5L-II
Mount: AZ-EQ6
Mount Control: EQASCOM
Focusing: SharpSky Pro and Sequence Generator Pro 3 (automated)
Bahtinov Mask: No
Capture Software: Sequence Generator Pro 3
Guiding Software: PHD2
Calibration and Stacking Software: PixInsight
Processing Software: PixInsight
Number and Type of Data Frames: L= 19X300 sec, L =7X120 sec, L= 14x30 sec, R= 10x180 sec, G= 10x180 sec, B= 10x180 sec
Ha= x , SII= x , OIII= x .
Binning: 1x1
Total Image Time: 206 minutes
Location: Lockleys Observatory B, Tanunda, Sth Australia
Light Box by Exfso
Finally got some colour for my NGC104 image. Not very much or not as much as I wanted although for now it will have to do. Still struggling with focus, will try to get out under the moon and nail the Temp Compensation and see how that goes.
Details
Telescope: William Optics FLT132
Guide Scope: QHY OAG
Camera: QHY9 Mono @ -20c
Filter Wheel: QHY 7 position Ultra Slim
Filters: QHY 36mm unmounted L R G B HA OIII SII
Guide Camera: QHY5L-II
Mount: AZ-EQ6
Mount Control: EQASCOM
Focusing: SharpSky Pro and Sequence Generator Pro 3 (automated)
Bahtinov Mask: No
Capture Software: Sequence Generator Pro 3
Guiding Software: PHD2
Calibration and Stacking Software: PixInsight
Processing Software: PixInsight
Number and Type of Data Frames: L= 19X300 sec, L =7X120 sec, L= 14x30 sec, R= 10x180 sec, G= 10x180 sec, B= 10x180 sec
Ha= x , SII= x , OIII= x .
Binning: 1x1
Total Image Time: 206 minutes
Location: Lockleys Observatory B, Tanunda, Sth Australia
Light Box by Exfso
With temp compensation I found keeping a log of the temperature and the focus positions and then working out an average number for the shift of focus/ degree C worked pretty well. It does assume focus shifts are linear and they probably are initially then they flatten off (I think or at least they seem to with my scope). Most likely due to a closing of the difference between ambient and the temp of the objective.
For example my CDK17, when the temp difference is more than 1C it will not be spot on focus but once its within .5C it reaches a peak and focus is sharp.
Just looking at the numbers, the background has quite a blue cast, but even if I fix that, the glob is slightly too blue. Although globulars contain a smattering of very salient blue stars due to mergers, globulars, with their extreme age of around 10 billion years, cannot on average be blue, because blue stars are so hot they only live a million years or so.
You've achieved better colour differentiation/separation than what I have in the stars which is good
Resolution is good but you've got the same problem that I did with an overly bright core (it is a very bright core mind you).
Resolution looks good Gray. I agree with the comments about the blue background cast. The histogram has blue to the right of the mid point. As Mike said, the cluster has mainly old main sequence stars and a smattering of blue stragglers. If you adjust the blue, the bulk of the stars looks white with notable blue stragglers and a few orange giants. Back ground comes up charcoal then.
First up, very, very nice image Bart. Congratulations.
Quote:
Originally Posted by Paul Haese
Resolution looks good Gray. I agree with the comments about the blue background cast. The histogram has blue to the right of the mid point. As Mike said, the cluster has mainly old main sequence stars and a smattering of blue stragglers. If you adjust the blue, the bulk of the stars looks white with notable blue stragglers and a few orange giants. Back ground comes up charcoal then.
The thing that one has to bear in mind about "blue straggler" is that they are blue in a comparative sense and very rarely if ever actually "blue" -- ie have a B-V trace in the negatives. Most blue stragglers are currently believed to be merger remnant stars that are the result of two smaller stars colliding and/or merging or as a result of mass-transfer in a tight binary system. While stellar collisions/mergers are a vastly improbable event among the general population of stars in our galaxy, it is unlikely but does happen within the very, very dense cores of globular clusters and even in some dense open clusters where the distance between individual stars can be measured in light-hours as opposed to light-years.
Typically blue stragglers are F-type or at best very late A-type stars with a mass between 1 and 1.6 solar masses. The turn-off point (from the main sequence) for most genuine G.Cs is in the mid to late G-type (ie about 0.8 solar-masses). As I said, blue stragglers are generally not genuinely blue, but comparatively blue and anomalously blue when compared to the other brighter member stars in the cluster (that are typically red AGB-tip stars). I would think that proper processing would render most of, if not nearly all these stragglers as white or very light yellow as opposed to blue. There might be a very few actually blue stars in a typical G.C that are, in the main, horizontal branch post AGB stars (and probably RR Lyrae-type variables) powered largely by the triple alpha process.