Faint Galaxies (M99 etc) taken at D'Kranji farm resort (07 Jun 2015)

[PETER LOO]

Hi all, apologies for the inconvenience caused by my FB being down since last year Dec. Here are 3 galaxies (all in 1) taken some 8 years ago with the company of Gary Koh, Carol and Alex Lee over beers at then D'Kranji farm resort. Gary would set up his then brand new ZEQ-25 mount and myself GPD2 Mount with TS-90 scope. Shooting data: Date was 07 Jun 2015, cam: Canon 500D-mod, ISO 1600, 90s X 20 subs selected. Sky seems darker then.

[PETER LOO]

M101 Pinwheel Galaxy: low surface brightness of 14.86 mag/arc-min(SQ), low contrast index of -0.62, hence a fairly difficult object for SG sky
Changi Beach 19 May 2013
Mount used: Vixen GPD2 with Star Book-S GOTO system
Scope: Meade ED80APO, 80/480 mm, No flattener ! (and no flat field being done)
Cam: Canon550D no mod, ISO 1600 60s X 33; ISO 800 60s X24

n.b. top image has been cropped
bottom image original framing

[Airconvent]

Good capture ! BTW, what is that dark patch in the lower frame ? Cloud or sensor dust ?

[PETER LOO]

Thanks Airconvent, is sensor dust, after stacking looks elongated.
As for the vertical lines, they are read out noise, used 2 different cam at D'Kranji site and Changi Beach site made the difference. The Canon 550D (M101) has less read noise, that may also be partly due to 'natural dithering' of mount at Changi (no guiding) but had produced a large black frame after stacking.

[PETER LOO]

M83 - Southern Pinwheel galaxy, which is relatively brighter, taken at then Bedok South field on 03 May 2014 (now no more)
Mount: GPD2 guided. Scope: TS 90/600 mm
cam: Canon 500D mod. ISO 16000, 120s X 21

Top image is stacked
Bottom image shows single frame (CR2) of 120s stretched

[Airconvent]

Thanks Peter. I you change lens often, a good practice to activate the build in sensor sonic cleaning after lens replacement Nice processed image!

[PETER LOO]

Thanks Richard, noted. Ya, dust does get in easily while take in take out of the camera. Meanwhile, i am considering to capture the M81 + M82 galaxies with 200mm f2.8 lens on Canon DSLR working with the Skyguider-pro mount. Planned next year Mar to May period. As these object can only climb up to around North 22 deg over here, i am thinking of going to Changi Beach park (good dark North view) or rent a chalet at CSC club. Since the galaxies are accompanied by a mag 4.5 star in the FOV and a few other bright stars forming pattern, it is easy to find and then manual plate solve the object without the need of a GOTO mount nor Software, the mount just need to be RA driven and with a reasonably good polar alignment will be enough for 1 to 2 mins subs collection. Only worry is the cloud. (cloudy nights)