Viewing Report 7th April 2020 – IMT3 – TPoint Failed

Viewing time period – 20:54 – 22:30

Old TPoint Model before new run

Tonight I set out to perform a TPoint run to improve the values we got last October. However it transpired to be more difficult than I thought. We updated TSX after October to there latest release, this seemed to have changed some of the parameters for plate solving. This meant that every time we took an image in the TSX it would not plate solve and so we could not perform the TPoint run. After the best part of 1 hour I gave up and let Bob take over the scope to play.

Meanwhile I then setup the Mac 180 to image Venus, however, by the time I got round to it and found it in the telescope and thus on the chip it was low down the side of the house opposite by the roof and was bumping around badly due to thermals. I found it difficult to centre the scope on Venus with such a small chip so I may need a more repeatable way of doing this moving forwards. I took a couple of videos just for posterity even though I felt the quality would be poor.

Subsequently the following day I opened up the images take with TSX and also download the All Sky Database that was missing to both the NUC in the dome and my local Mac. I then started to change the settings in Image Link within TSX until I could solve the image.

Solved image using Image Link All Sky Search in TSX

The key parameter transpired to be the Image Scale Tolerance on the All Sky tab setting it to 5% from 1%. Also I changed the Image Scale back to 0.32. On the Setup tab I selected Setup under Source Extraction and changed the detection to 10.0 and the minimum number of pixels to 20.0.

New Source Extraction Settings and solved image

I then tried a second image and that solved in 1 sec too so very happy. I will try to give the TPoint another go tonight as well as Venus on the Mac 180. If TPoint works I will take RGB on the Tak. First solution from the image I solved can be seen below.

TSX Image Link solved

The resulting astrometric solution from TSX is below based on another 60s exposure image is below as text.


Center RA (2000.0): 07h 14m 12.34s

Center Dec (2000.0): +32° 34' 16.1"

Scale: 0.3250 arcseconds/pixel

Size (pixels): 4656 x 3520

Angular Size: 0° 25' 13" x 0° 19' 04"
Position Angle: 195° 28' from north through east

Mirror Image: No

RMS: 0.88 (X: 0.45 Y: 0.75)

Number of Stars Used in Solution: 40 (100%)

FWHM: 8.98 pixels, 2.92 arcseconds


Things still to resolve

  1. Check out why WSX is loosing connection and shutting the dome
  2. Clean filters for the 12″ to get rid of doughnuts
  3. Clean sensor for QHY168C