Mr Ian David Sharp

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Viewing 20 posts - 1 through 20 (of 87 total)
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  • in reply to: AT2024bch – A potentially bright supernova in NGC3206 #621509
    Mr Ian David Sharp
    Participant

    Thanks Robin,

    I measured it at V=14.59 and R=14.52 last night (2024-01-31 00:30)

    Cheers
    Ian.

    in reply to: 2023 – how was it for you? #621174
    Mr Ian David Sharp
    Participant

    Hi all,

    Difficult to quantify, but one statistic I can quote is that I submitted 37,974 variable star measurements to the BAA Photometry database during 2023. This may sound a lot, but I regularly upload 100+ data points in any one observation as I focus on PCEB systems.

    It’s only because I have a system in Spain that I was able to do this. Having said that, there was a period from late May for 6 weeks in the UK where I had almost entirely clear skies.

    Cheers
    Ian.

    in reply to: PHOEBE2 Eclipsing Binary Modeling Software – Help! #621007
    Mr Ian David Sharp
    Participant

    Have you tried the AAVSO ? I may be mistaken but I seem to remember that Bert Pablo, the staff astronomer, had some involvement with the development of PHOEBE2.

    Hi Tony,

    That’s a very good idea – thanks, I might try that.

    In actual fact, I have persisted with this myself and I am now making quite good progress. I have finally managed to understand some of the key concepts and am getting some results out of Phoebe. This is good as I won’t have to ask so many very basic questions if I do contact someone.

    Cheers
    Ian.

    in reply to: Betelgeuse #620676
    Mr Ian David Sharp
    Participant

    Folks,
    My initial thoughts after successfully observing the occultation last night:

    Excellent! Certainly more interesting than my drift trail!

    Cheers
    Ian.

    in reply to: Betelgeuse #620670
    Mr Ian David Sharp
    Participant

    Well, here’s my 60 second drift image with an OIII filter. I had no saturation (this image is slightly stretched). I see no sign of any dimming.

    Cheers
    Ian.

    Attachments:
    in reply to: Betelgeuse #620666
    Mr Ian David Sharp
    Participant

    Drift is a good option. Driftscan software can process your capture. Please record for about 1 minute before and after the mid-time given by the Interactive Map of the Paris ‘Lucky Star’ prediction

    Thanks Alex,

    I’m experimenting now. I can record (drift) for just over a minute which will be only 30 seconds or so either side of my predicted mid time. The only filter that does not saturate is my OIII giving me ADU values of about 30,000.

    Cheers
    Ian.

    in reply to: Betelgeuse #620641
    Mr Ian David Sharp
    Participant

    Hi all,

    It looks like the occultation track of Leone tonight passes over my telescope at PixelSkies in Spain.

    Having a C11 with an SX694 TRIUS CCD, I can’t take short, rapid exposures a la a CMOS camera, so my plan is to let it drift across the FOV. I will experiment first with am R filter but I suspect it will easily saturate. Then I will try an SII. All slightly off focus I think.

    Any other tips?

    Cheers
    Ian.

    in reply to: NUCs and Minipcs #620577
    Mr Ian David Sharp
    Participant

    Hi Grant,

    Yes, I have several mini PCs on my various rigs. I like the ones from Beelink and also the MELE Quieter series which are fanless and silent.

    This Beelink is under 200 quid! : https://tinyurl.com/bddzz49d

    Cheers
    Ian.

    in reply to: Another Comet 12P outburst? #620220
    Mr Ian David Sharp
    Participant

    Thanks Nick,

    Here’s my image from last night.

    Cheers
    Ian.

    in reply to: Another Comet 12P outburst? #620194
    Mr Ian David Sharp
    Participant

    I also got another image last night. I captured the dark streak nicely, but my processing does not seem to have shown the blobs.

    Cheers
    Ian.

    in reply to: SN 2023ixf in M101 Mag is rapidly dropping again! #620187
    Mr Ian David Sharp
    Participant

    Thanks Robin,
    Ian.

    in reply to: Another Comet 12P outburst? #620179
    Mr Ian David Sharp
    Participant

    Hi all,

    I managed to image 12P last night from Spain. Here is a stack of 20 x 60 secs with an L filter. North is to the left. Image is 18′ x 14′ (0.48 “/pix).

    The nucleus is very bright!.

    Cheers
    Ian.

    in reply to: Software for photometry (image calibration) #620116
    Mr Ian David Sharp
    Participant

    I don’t know what stretching is.

    Ah! then you have to learn about this!

    Astronomical deep-sky images contain mostly black (or near black) sky. When you view an image un-stretched astronomical image you see virtually nothing – just a few pin pricks of light from the brightest stars. This is because most of the data is residing near the black-point of the ‘histogram’. But applying a non-linear stretch to the image, the data is spread more evenly across the histogram from the black point to the white point.

    See my attached screen shot. The image on the right is a clone of the one on the left but I have applied a histogram stretch to the one on the right. Without this skill you will not be able to see your data properly, nor be able to check the calibration properly.

    I feel you have learning curves all over the place! If you would like a Skype or Zoom (or similar) call I could share my screen and take you through a few things? Otherwise there will be a lot of back and forth with messages etc.

    You can PM me here if you want to set something up…

    Cheers
    Ian.

    Attachments:
    in reply to: Software for photometry (image calibration) #620101
    Mr Ian David Sharp
    Participant

    Hi Kevin,

    Further to this, as Grant has mentioned, compare your uncalibrated lights to your calibrated lights. See my attached image where I show three heavily stretched images. Top left is uncalibrated – note the gradients and the dust marks. Top right is calibrated – note it looks pretty flat. Bottom is the flat frame with a big stretch.

    Not the most dramatic example because my C11 has a pretty flat field over this sensor to start with. But – I must try and get rid of that horrible splodge on the sensor!

    Cheers
    Ian.

    Attachments:
    in reply to: Software for photometry (image calibration) #620100
    Mr Ian David Sharp
    Participant

    So the image it outputs, is that a calibrated image? Is it possible to tell?
    What does the software do to the original uncalibrated lights?

    Hi Kevin,

    ASTAP does nothing to your uncalibrated lights and it creates calibrated copies with “_cal” on the end of the file names.

    If you look at the FITS headers of the calibrated files, you will see something as shown below towards the end of the header. In my test I only selected my master dark and master flat files and you can see resulting CALSTAT = ‘DF’. Also the COMMENT 1 field indicates it was calibrated by ASTAP.

    What do you see in the CALSTAT field when you use your flat-darks?

    Cheers
    Ian.

    COMMENT 1 Calibrated by ASTAP. http://www.hnsky.org
    PEDESTAL= 5.000000000000E+002 / Value added during calibration or stacking
    CALSTAT = ‘DF’
    DARK_CNT= 1 / Darks used for luminance.
    FLAT_CNT= 1 / Flats used for luminance.

    in reply to: Software for photometry (image calibration) #620092
    Mr Ian David Sharp
    Participant

    SIMPLE = T / file does conform to FITS standard
    Which I know is a bit of a deal breaker as they have to conform. So that’s where I am. Any thoughts please?

    Hi Kevin,

    I don’t understand the problem. It all looks OK to me. Here, for comparison, is one of my FITs headers after it’s been calibrated. (Captured in SG Pro, calibrated by AA8).

    Cheers
    Ian.

    SIMPLE = T / file does conform to FITS standard
    BITPIX = 16
    NAXIS = 2
    NAXIS1 = 2750
    NAXIS2 = 2200
    BZERO = 32768.0
    BSCALE = 1.0
    CRPIX1 = 1375.999999978
    CRPIX2 = 1100.999999981
    CTYPE1 = ‘RA—TAN’
    CTYPE2 = ‘DEC–TAN’
    OBJECT = ‘CF PEG ‘ / Object name
    DATE-LOC= ‘2023-10-08T21:50:30.3930000’ / Local observation date
    DATE-OBS= ‘2023-10-08T19:50:30.3930000’ / UTC observation date
    IMAGETYP= ‘LIGHT ‘ / Type of frame
    CREATOR = ‘Sequence Generator Pro v4.2.0.1158’ / Capture software
    INSTRUME= ‘Starlight Xpress H694’ / Instrument name
    ROWORDER= ‘BOTTOM-UP’
    OBSERVER= ‘Ian Sharp’ / Observer name
    SITENAME= ‘PixelSkies’ / Observatory name
    SITEELEV= 850 / Elevation of the imaging site in meters
    SITELAT = ’37 44 23.000′ / Latitude of the imaging site in degrees
    SITELONG= ‘-0 38 38.000’ / Longitude of the imaging site in degrees
    FOCUSER = ‘PegasusAstro ProdigyMF’ / Focuser name
    FOCPOS = 5489 / Absolute focuser position
    FOCTEMP = 19.48 / Focuser temperature
    FWHEEL = ‘Starlight Xpress Filter Wheels’ / Filter Wheel name
    FILTER = ‘L ‘ / Filter name
    EXPOSURE= 60 / Exposure time in seconds
    CCD-TEMP= -10.2 / Camera cooler temperature
    SET-TEMP= -10 / Camera cooler target temperature
    XBINNING= 1 / Camera X Bin
    CCDXBIN = 1 / Camera X Bin
    YBINNING= 1 / Camera Y Bin
    CCDYBIN = 1 / Camera Y Bin
    XPIXSZ = 4.5390625 / Pixel Width in microns (with binning)
    YPIXSZ = 4.5390625 / Pixel Height in microns (with binning)
    STRSZ1x1= 6 / SGPro minimum star size filter
    READOUTM= ‘Standard Readout Mode’ / Camera readout mode
    TELESCOP= ’10Micron Mount’ / Telescope name
    RA = 325.297497442515 / Object Right Ascension in degrees
    DEC = 26.2268339926879 / Object Declination in degrees
    CRVAL1 = 325.2979715357
    CRVAL2 = 26.20068031717
    OBJCTRA = ’21 41 11.399′ / Object Right Ascension in hms
    OBJCTDEC= ‘+26 13 36.602’ / Object Declination in degrees
    PIERSIDE= ‘West ‘ / Side of Pier the objective is on
    AIRMASS = 1.04170531837155 / Average airmass
    OBJCTALT= 73.8212777777778 / Altitude of the object
    CENTALT = 73.8212777777778 / Altitude of the object
    FOCALLEN= 1956 / The focal length of the telescope in mm
    FLIPPED = F / Is image flipped
    ANGLE = 267.83 / Image angle
    SCALE = 0.472905 / Image scale (arcsec / pixel)
    PIXSCALE= 0.472905 / Image scale (arcsec / pixel)
    AOCDEW = 10.3 / Dew Point in degrees C
    AOCHUM = 75 / Humidity in %
    AOCRAIN = 0 / Rain Rate in mm/hr
    AOCSKYT = -28.5 / Sky Temperature in degrees C
    AOCAMBT = 18.7 / Ambient Temperature in degrees C
    AOCWIND = 12.5833333333333 / Wind Speed in m/s
    EGAIN = 0.3 / Electrons Per ADU
    STAR = ‘CF PEG’
    PROCESS = ‘DK+FLAT’
    CALSTAT = ‘BDF’
    EQUINOX = 2000.0
    CD1_1 = 4.981204779451E-006
    CD1_2 = -0.0001310849482926
    CD2_1 = -0.0001310385252376
    CD2_2 = -4.948753747364E-006
    CDELT1 = -0.0001311331670384
    CDELT2 = 0.0001311783283646
    CROTA1 = 0.0
    CROTA2 = -87.83051432587
    AVISUMIN= -33.0
    AVISUMAX= 467.0
    AVISUTYP= 0.0
    END

    in reply to: Software for photometry (image calibration) #620079
    Mr Ian David Sharp
    Participant

    I thought it was the case that when Windows Defender objected to something you could bypass it by choosing the other option (which isn’t highlighted and doesn’t say “bypass” 🙂 ).

    Ah, I know the one you mean now – the one where you have to go into an option and choose “Run anyway”. Yes, that often happens.
    Ian.

    in reply to: Software for photometry (image calibration) #620073
    Mr Ian David Sharp
    Participant

    A few first impression comments about the suggestions. Working my way through them.

    ASTAP intiates a Windows Defender warning.

    Calibration Intro Tutorial for Tycho Tracker seems to suggest it’s for moving targets.

    I have installed AstroImageJ, found the DP button but there is no option to process flat darks.
    So I have found various tutorials but I’m getting the impression they are for CCDs which do use bias frames I believe.

    Trying not to be too negative but I think I need something with very basic tutorials that walks you through it.

    Kevin

    Hi Kevin,

    I run ASTAP on 3 different PC’s and I’ve never seen a Windows Defender warning. ASTAP does deal with flat-darks as far as I can see but, as I said, I use PixInsight to create my master calibration files.

    Tycho Tracker handles both static and moving targets, but I’m not sure it deals with flat-darks – I might be wrong.

    I think you’re right about AstroImageJ – why not experiment with Bias frames and see what you get?

    Lastly, I’ve found this calibration tool which looks interesting:

    https://astrohobby.ca/my-software/calights/

    Cheers
    Ian.

    in reply to: Software for photometry (image calibration) #619890
    Mr Ian David Sharp
    Participant

    Hi Kevin,

    There are quite a few choices for software packages that will calibrate your images, and some will calibrate and perform the photometry. Did I see somewhere that you are learning to use the AAVSO VPhot software? I don’t believe that has calibration facilities? It’s amazing on the calibration side of things.

    I, personally, use AstroArt 8 (AA8) for my photometry and this is because it can be scripted and controlled by my Python programs. AA8 also performs the calibration. I prefer to use PixInsight to produce my calibration master files, but that’s only because I’m well versed in PI and it has an incredible set of calibration processes. AA8 would do the job too.

    Having said all this, I’ve recently been using the excellent Tycho Tracker program to do photometry. This also copes with calibration. I would recommend looking at this and there are lots of very good videos on YouTube by the author of the Tycho software and he is very responsive with questions. There is a small one off cost for the Pro version but it is well worth a look.

    Other than that, there is Maxim DL which is widely used for calibration and photometry. Also AstroImageJ (free) is incredible but takes a bit of learning.

    You could use the free DeepSkyStacker for calibration.

    I know lots of people swear by Siril which I believe is free.

    A few links:

    https://www.tycho-tracker.com/
    https://siril.org/
    https://www.astro.louisville.edu/software/astroimagej/
    http://deepskystacker.free.fr/english/index.html

    Cheers
    Ian.

    in reply to: Bias Frames for CMOS #619886
    Mr Ian David Sharp
    Participant

    Just to clarify
    My flats taken with a light pad and T-shirt required exposures of 2.3 sec to get the histogram max
    between 1/3 and 1/2 of max ADU count.
    That means I need to take a set of darks at the same exposure (all other things as you say replicated, temp gain etc.)

    Hi Kevin,

    Yes, that’s correct – you need darks to match your flats (and darks to match your lights of course!). My exposures vary from about 2 to 8 seconds with my CCD based system with my LED screen.

    Cheers
    Ian.

Viewing 20 posts - 1 through 20 (of 87 total)