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Comet 46P Wirtanen - close approach to Messier 45 on the 16th December 2018

Samyang 135 f/2 at f/2.8

Astro-modified Canon 80D at ISO400, IDAS clip-in LPS D2 filter, 7 x 3 minute subs.

NEQ6 pro mount with Rowan belt drives -1 star align.

Mini-PC with WiFi

Mount WiFi control with ASCOM/AstroPhotography Tool

Camera WiFi control with Backyard EOS

 

22 dark frames

45 flat frames (electroluminescent panel @ 1/200s)

Master bias from library.

 

Post processed in PixInsight 1.8 and Photoshop

 

Local parameters:

Temp: 5.4- 5.7c

Humidity: 81- 84%

Pressure: 1000.4 kPa

 

Camera Sensor Temp: 12-13c

 

Light Pollution and Weather:

First quarter Moon.

Initially cloudy and hazy, gradually cleared. Significant moonlight gradient.

 

Polar Alignment:

QHY Polemaster alignment -

Error measured by PHD2= 1.4 arc minute.

RA drift + 2.24 arcsec/min

Dec drift - 0.37 arcsec/min

 

Guiding:

PHD2 guiding with ZWO ASI290mm/Altair Starwave 206/50mm guider.

RA RMS error 0.84 arcsec, peak error -2.76 arcsec

Dec RMS error 0.44 arcsec, peak error -2.19 arcsec

 

Astrometry:

Center (RA): 03h 55m 12.061s

Center (Dec): +24° 11' 56.918"

Size: 5.4 x 3.56 deg

Pixel scale: 9.71 arcsec/pixel

 

Not happy with eccentric haloes around brighter stars - present here with 135mm lens and also 480mm scope so I'm reasonably sure it's the culprit now. I have a 2 inch screw-in filter that I can place in front of my focal flattener on the 480mm scope - will see if that fixes problem.

 

Update 10/2019 - other people have mentioned problems like this with the Samyang 135mm f/2 - have changed to Sigma 135mm f/1.8 because of this - much happier. If nothing else can tightly adjust focus in BackyardEOS.

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Uploaded on December 18, 2018
Taken on December 19, 2018