What to Photograph in Autumn: September to November
Andromeda gets all the attention and deserves some of it. But autumn's real gift is a run of large, bright nebulae arriving just as the nights get long enough to use them properly.
Autumn is the most comfortable imaging season of the year and the most underrated. The nights lengthen rapidly through September and October, the air cools without yet being hostile to batteries, and the sky delivers a sequence of large targets that suit wide-field instruments almost perfectly.
It is also the season with the clearest beginner trap in it, which we should deal with first.
Andromeda is bigger than you think
M31 is the most photographed galaxy in the sky and the one most likely to produce a disappointing first result, for a reason nobody warns beginners about: it is enormous. The full extent of Andromeda spans roughly six times the width of the full moon. On many smart telescopes it will not fit in the frame at all.
This produces a specific failure mode. You point at Andromeda, you collect an hour, and you get a bright fuzzy core filling the middle of your image with the interesting structure cropped off at the edges. The result looks less impressive than a nebula that is objectively harder, and beginners conclude they did something wrong.
You did not. You framed a target that is too large for the field. The options are to accept a partial frame deliberately composed, to use a mosaic mode if your instrument offers one, or to treat M31 as a target for a shorter focal length than you own.
What does work: give it enough integration that the dust lanes separate cleanly, because those lanes are the whole visual interest, and they need signal to emerge from the core's glare.[1]
The Pacman, Heart and Soul: autumn's easy nebulae
Cassiopeia rides high through autumn evenings and carries three excellent targets that behave exactly the way a smart telescope wants them to.
NGC 281, the Pacman Nebula, is compact enough to frame comfortably and bright enough in hydrogen-alpha that a dual-band filter produces a strong result in ninety minutes from a suburban sky.
The Heart and Soul nebulae are the opposite: enormous, faint, and better suited to the widest field you own. On many instruments the Heart alone fills the frame. They reward integration time steeply and are a good multi-night project.
All three are circumpolar or near-circumpolar from northern latitudes, meaning they are up all night and you can schedule around the moon rather than around the clock.
The Triangulum Galaxy, the honest challenge
M33 is a face-on spiral, which sounds ideal, and it is one of the harder targets in this article. Face-on means its light is spread across a wide area rather than concentrated, so its surface brightness is low despite a respectable total magnitude.
From a light-polluted site it is genuinely difficult. From a dark site with two or three hours it is spectacular, with distinct spiral arms and knots of pink star-forming regions. It is the best single measure of how dark your sky actually is.
The Double Cluster, when you want a quick win
NGC 869 and NGC 884 in Perseus are two open clusters sitting side by side, and they are the antidote to a frustrating night. Twenty minutes produces a genuinely attractive image. There is no faint structure to chase, no filter decision to agonise over, and the result looks good immediately.
Every imaging session should have one of these in reserve. When the target you planned is behind cloud, or the session has gone wrong in some way you cannot diagnose at midnight, point at the Double Cluster and go to bed having made something.
Why autumn is the season to plan a dark-sky trip
Two things line up. The nights are long enough to justify the drive, and the targets that most need dark skies, M33 and the Heart and Soul in particular, are all well placed. Meanwhile the weather at many sites is more settled than in spring, and the cold has not yet reached the point where battery management dominates the evening.
If you make one trip to a certified dark-sky site a year, October is a strong candidate. Plan it for the week around new moon, check the forecast for transparency rather than just cloud cover, and go with two targets rather than six.
Notes & sources
- M31's angular extent of roughly three degrees and the framing implications for short focal-length instruments. Sky & Telescope, Astrophotography tips ↩