Affiliation
British Astronomical Association, Variable Star Section (BAA-VSS)
Tue, 01/23/2024 - 20:24
I just had what I thought was my first success at calibration using ASTAP.
I tried to upload the file to VPhot. It seemed to upload with an active loading bar.
When I looked for it, not there.
I noticed that they are suffixed as FITS files whereas the raw files are FIT and these upload fine.
Any help please?
Kevin:
Open one of each file (before and after calibration). Compare the fits headers.
Report what headers have changed.
There will be some new calibration related headers.
Have any disappeared?
Ken
Hello Ken,
Thanks for trying to help once again.
There are many, many differences between the headers of the calibrated and original images
Near the start
BITPIX = 16 / number of bits per data ORIGINAL
BITPIX = -32 / number of bits per data pixel CALIBRATED
BZERO = 32768 / offset data range to that of unsigned short ORIGINAL
BZERO = 0 / offset data range to that of unsigned short CALIBRATED
Then they are the same to the END of the ORIGINAL, but the calibrated then has several pages of additional lines.
This is very frustrating. I am using ASTAP for calibration as it seemed very user friendly.
I tried for hours/days but I can't seem to make any progress with
AIP4WIN, ASTROimageJ, Deep Sky stacker as none of them have any kind of tutorials/examples.
++++++++++++++++++++++ ADDITIONAL TEXT TO CALIBRATED (There's a lot) ++++++++++++++++++++++++
COMMENT 1 Written by ASTAP. www.hnsky.org
PEDESTAL= 0.000000000000E+000 / Value added during calibration or stacking
CALSTAT = 'DFBS'
DATE-END= '2024-01-18T18:23:34'/ Date and time of the end of the observation.
JD-AVG = 2.460328265080E+006 / Julian Day of the observation mid-point.
DATE-AVG= '2024-01-18T18:21:43'
EXPTIME = 180 / Total exposure time in seconds.
COMMENT D=master_dark_3x60s_at_-5C_2023-11-18.fit
COMMENT F=master_flat_corrected_with_flat_darks_V_3xF_3xFD_2024-01-11.fit
HISTORY 1 Stacking method AVERAGE
HISTORY 2 Processed as gray scale images.
SET-TEMP= -5 / Average set temperature used for luminance.
LUM_EXP = 60 / Average luminance exposure time.
LUM_CNT = 3 / Luminance images combined.
LUM_DARK= 3 / Darks used for luminance.
LUM_FLAT= 3 / Flats used for luminance.
LUM_BIAS= 3 / Flat-darks used for luminance.
DATAMIN = 0 / Minimum data value
DATAMAX = 64902 / Maximum data value
CBLACK = 0 / Black point used for displaying image.
CWHITE = 2969 / White point used for displaying the image.
END
I have used ASTAP for over a year to calibrate and stack images. I have submitted them to VPhot without problems. It has been around 8 months since I last did it.
I assume you ran it through the VPhot interface to check if the header was valid? Have you tried submitting again since the first failure? VPhot seems to act up now and again and it is worth a second try.
Bill
Thanks Bill,
Not sure what you mean by running it through the interface. I there another way to check the files are VPhot compliant?
I just used upload (both way) wizard and quick. Both have worked fine for all other FIT files in the past.
The first couple of header differences look a bit suspicious to me.
BITPIX = -32 / number of bits per data pixel
Minus 32 bits per pixel??????
BZERO = 0 / offset data range to that of unsigned short
This is 32768 in the original file headers
Kevin
Sorry, I wasn't clear. The Upload Wizard is the UI that helps you figure out if your image meets requirements. I haven't used VPhot in a while and forgot the name.
The -32 BITPIX means the pixel values have been converted to floating point values. ASTAP does that. VPhot should be able to handle that unless it's changed in the past 8 months. The change in BZERO may relate to the conversion to floating point.
I just recalled I initially had a problem similar to what you are seeing. It turns out I needed to add
EQUINOX = 2000.
into the header. Your capture software should really do that but you can add it with ASTAP.
I tried that but I'm afraid it didn't work.
Thanks for your suggestion.
Kevin
It's a shame because I find ASTAP very user friendly, unlike any of the others I have tried.
I thought I was very close to uploading my first calibrated photometry observation.
I wonder if it's one of the many settings (default which I haven't touched) in the programme.
Kevin
Kevin;
Are your settings in your own Vphot Telescope Setup page correct for your images, (e.g., image scale)?
What do you have for your system name and display name and how do they compare to your similar image fits headers (e.g., TELESCOP)?
BTW, it may be more effective to use direct email than the forum since screenshots and files can be attached?
Ken
Sorry to hear that. I don't think the problem is ASTAP. There must be something else wonky in the header. It's shame VPhot does not give a better error message.
It's worth a try.
Steve - HSTG
Just to let others know that thanks to Ken's and Steve's suggestion we discovered that VPhot may not accept
the lengthy file names output by ASTAP calibration software, which also adds other characters like commas.
It was actually the commas and brackets and any non-letter character that caused the problem. I'm not sure why ASTAP does that, but problem solved.
Thanks Ken and Steve.
Kevin