What to Photograph in Spring: March to May

Spring is the season that most tests a smart telescope, because as Orion sets in the west the sky behind it is almost entirely galaxies. Nebulae are large, bright and often glowing at specific wavelengths a filter can isolate. Galaxies are small, faint, broadband, and utterly unforgiving of light pollution. A dual-band filter that transformed your winter will do nothing for you in April.

That is the bad news. The good news is that a handful of spring galaxies are genuinely well suited to these instruments, and one of them is arguably the most satisfying target in the entire year.

Why galaxies are harder

Three things work against you at once.

They are small. A smart telescope's wide field is a gift on the Rosette and a liability on a galaxy that spans a tenth of the frame. Most spring galaxies will occupy a modest patch in the middle of your image, and the resolution you can bring to bear on that patch is limited by the optics rather than by your patience.

They are broadband. Galaxy light is starlight, spread across the whole visible spectrum, and so is light pollution. There is no clever filter that separates them. This is the fundamental reason dark skies matter more in spring than at any other time.^[1]

They reward integration steeply. A nebula looks decent after forty minutes. A galaxy at forty minutes looks like a smudge that could be a processing artefact. The same galaxy at three hours has spiral structure. The curve is much less forgiving.

M81 and M82: the pair that works

Start here. Bode's Galaxy and the Cigar Galaxy sit close enough together to share a single frame at smart-telescope focal lengths, which turns the small-target problem into an advantage: instead of one modest smudge in a large field you get a composition, two contrasting galaxies with genuine visual interest between them.

They are also circumpolar from most northern latitudes, meaning they are available all night and most of the year, and they are bright by galaxy standards. Ninety minutes gets you a clean, obviously-real image. Three hours starts to show the dust lanes in M82.

The Whirlpool, M51, when you are ready

M51 is the target people mean when they say galaxy season. A face-on spiral with a companion galaxy caught mid-collision, it is the picture that made a generation want a telescope.

It is also a genuine test. The spiral arms need real integration time and a reasonably dark sky to separate from the background. Under Bortle 6 with an hour you will get a bright core and a suggestion of structure. Under Bortle 4 with three hours you will get arms.

My advice is to attempt it in your first spring anyway, save the result, and attempt it again the following spring. The comparison is the single best measure of how much you have learned.

The Leo Triplet, for composition

Three galaxies in one field: M65, M66 and NGC 3628. Like M81 and M82, the appeal here is that the framing does the work. None of the three is individually spectacular, but together they make an image that looks deliberate.

NGC 3628, the Hamburger Galaxy, is the faintest of the three and the one that tells you whether your session worked. If its dust lane is visible you had a good night.

Markarian's Chain, the ambitious one

A curving string of galaxies in Virgo, part of the Virgo Cluster, and the most rewarding wide-field galaxy target in the sky for an instrument with a generous field of view. This is where a smart telescope's wide field stops being a liability and becomes the whole point: you are not photographing one galaxy, you are photographing a structure made of galaxies.

It needs dark skies and patience, and it is worth planning a dark-sky trip around. If you get one clear moonless night at a good site this spring, spend it here.

What spring asks of you

Three habits matter more this season than any other.

• Chase the moon out of the sky. A first-quarter moon that barely affects the Rosette will flatten a galaxy completely. Spring imaging happens in the dark window, and planning around it is not optional.
• Put the filter away. Dual-band and light-pollution filters cut broadband light, and galaxy light is broadband. You will lose signal and gain nothing.
• Commit to fewer targets. Two galaxies at ninety minutes each beats five at thirty-five. Spring punishes the scattergun approach harder than any other season.

Galaxy season is the point where the hobby stops being about the equipment and starts being about the sky you choose to stand under. That is either a frustration or the beginning of the interesting part, depending on how you take it.

Notes & sources

1. Why broadband targets such as galaxies gain nothing from narrowband or light-pollution filters, and the resulting dependence on genuinely dark sites. Sky & Telescope, Astrophotography tips ↩