Bubble Nebula
NGC 7635 – Bubble Nebula

NGC 7635 – Bubble Nebula

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Acquisition Date: September 7, 2018

I really do like my uncooled Altair 290M camera but one thing is missing: a sensor temperature readout. This has stood in my way of creating a Darks Library. Having a Darks Library would free up my time to concentrate on capturing Light frames.

There is nothing worse than having to waste an hour collecting darks under the stars. Furthermore, I committed the sin of collecting darks after my lights when the temperature was usually much cooler (if anything, you should collect them before.) So I was getting sub-optimal noisy images with the hint of raining noise when the temperature of my darks were very different than my lights.

I decided to do something about it. I built a Temperature Logger with an Arduino, a high-precision temperature sensor having an accuracy of 0.25C, an SD card reader/writer, and a LIPO battery. I position the unit near my telescope. It records ambient temperature once per minute and writes it with a timestamp to the SD card. I’ve had it running for 11 hours straight on a single charge. It could probably go longer.

On those cloudy nights I collect darks. Then the following morning I download the image files and the temperature log, and segregate the image files by temperature. These past couple nights the weather cleared to try it all out. I like the results. Smoother, less noisy prints with no hint of raining noise.

Technical Details:

William Optics 71mm f/5.9
Altair 290M camera (uncooled)
Optolong luminance filter
Unitron Model 142 GEM
Passive tracking with PEC
No active guiding

Gain 100 (FWD: 15ke-, 3.66 e-/ADU)
Offset: 20 ADU
Exposure: 50s
Camera rotation: 3.8 deg E of N

Captured over 2 nights:
Luminance:
70.5 degF: 1 frame
71.0 degF: 22 frames
71.5 degF: 48 frames
72.0 degF: 4 frames
72.5 degF: 69 frames
Darks:
70.5 degF: 113 frames
71.0 degF: 69 frames
71.5 degF: 94 frames
72.0 degF: 96 frames
72.5 degF: 96 frames
Flats: 100
Bias: 100
Total integration time: 83 minutes

SharpCap 3.1.5219
PIPP 2.5.9
Deep Sky Stacker 3.3.2
StarTools 1.3.5.289

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