The Heart Nebula IC 1805

This is my astrophotograph of the glowing red emission nebula, IC 1805. When seen all at once, it has the outline of of a human heart; hence its nickname—The Heart Nebula. It is the small group of bright young stars at the centre, called Melotte 15, that illuminates this nebula. The Heart Nebula is located about 7500 light years away toward the constellations of Cassiopeia and Perseus.

I processed the data in natural colour (left) and in an approximate Hubble palette (right), as described here.

This image is the product of just 1.5 hours of useful data, collected as 5-min subs on a hazy night with too much passing cloud (any cloud is too much cloud!). Although I’m relatively pleased with the result under the circumstances, I think the short total integration time does show, and I’ve maybe pushed it too hard too. I did, however, want to blend it with the Fish Head Nebula IC 1795, which I photographed on 13 September 2020, and so I needed to balance the two frames before blending. This meant bringing the Heart Nebula up to the same brightness, noise and all, (or dimming the Fish Head and wasting the potential of the extra integration time I got on that target). The composite image below is the result of blending the two together.

Reprocessed on 9 February 2021

I reprocessed my Heart Nebula data from September and these are the resulting images. I wasn’t happy with the original version. The raw data suffers from high-altitude thin cloud, so I originally selected the best 1.5 hr, which wasn’t really enough. For reprocessing I used all 2 h 5 min of subs and hoped kappa-sigma clipping would sort out the rest. I’m now just about happy with these. It’s pretty the best I can do with my current skill set.


  • 25× 300-s light frames (Gain 900)
  • Full use of calibration frames (darks, flats and dark flats)


  • Explore Scientific ED 102 mm Apo f/7 refractor
  • Sky-Watcher EQ6-R PRO SynScan GOTO equatorial mount
  • Altair Hypercam 294C PRO colour fan-cooled camera
  • Altair quad-band one-shot colour (OSC) 2″ filter
  • Revelation Adjustable Field Flattener
  • Altair 60mm guide scope
  • Altair GPCAM2 AR0130 mono guide camera


  • Sharpcap
  • PHD2
  • DeepSkyStacker
  • Photoshop
  • Topaz Labs DeNoise AI
  • StarNet

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