M38 Open Cluster in Auriga: Sketching Compared with M52 in Cassiopeia

How the two clusters differ

What M38 looks like

M38 spreads across a field about a third of the diameter of the full Moon, so the cluster fills a moderate part of a low-power view. Its stars are scattered rather than packed together. You will see a loose group of individual stars with gaps between them, and the outline is irregular. Many members are faint, so the group reads as a patch of pinpoints that become clearer as your eye settles.

Because the cluster sits in a rich star field, the background stars can be as numerous as the cluster members. Decide early which stars belong to M38 and which are background. A practical rule is to draw the cluster members first, then add the background stars only where they clearly stand out from the Milky Way haze.

What M52 looks like

M52 is more compact. Its stars sit closer together, and the cluster has a denser core that stands out against the Milky Way behind it. When you sketch M52, the main decision is how to show density: you need to indicate where stars crowd together and where they thin out, rather than recording a loose spread.

Because the stars are packed tightly, it is easy to draw too many stars. Count the stars you can see in a small area first, and use that count to set the density across the rest of the drawing.

What the contrast teaches

M38 trains your sense of spacing and of the outline of a scattered group. M52 trains your sense of density and of how a core fades into the field. A sketch of M38 that gets the gaps right is a good test of accuracy, while a sketch of M52 that gets the density right tests your judgement of brightness levels.

Difficulty from a suburban sky

M38 has a total magnitude of 6.4, which is fainter than the naked-eye limit of about magnitude 5 that you can expect from a suburban sky. You will not see the cluster without optical aid. Binoculars can show it as a faint, hazy patch, but a small telescope is the more practical choice for sketching.

With a 70-90 mm refractor at low power, M38 is an easy target. The expected view is a group of individual stars, and most of the cluster's members should be visible. Faint stars at the edge of the group will appear only when you use averted vision, which means looking slightly to one side of a faint star so that its light falls on more sensitive parts of your retina.

M52 is also a manageable target from a suburban site, particularly when the Milky Way is well placed. Its core stands out more clearly than the outlying members of M38, so it can feel easier to start with. Background haze may still make the outer stars harder to separate, so keep your sketch limited to what you can confirm.

Do not oversell either target. In a suburban sky, both will look modest in a small telescope. A sketch that records an accurate, modest view is more useful than one that adds stars you only suspect are there.

Timing and sky position

M38 is best observed in January and February. In these months it is well placed in the evening sky for observers in the northern hemisphere, and it reaches its highest point in the early part of the night. Plan your session for the hours when the cluster is high enough to avoid thick, low air near the horizon.

Its altitude depends strongly on latitude. At 35° N it reaches a maximum altitude of 89°, almost overhead. At 50° N the maximum is 76°. Near the zenith, you may need to sit or recline to reach the eyepiece comfortably, so set up a reclining chair or a low stool before you start. At these latitudes, you can also observe the cluster from a site with a restricted view of the sky, since it does not need to be near the horizon.

At 35° S the maximum altitude is only 19°. From southern sites, M38 is a low target that stays close to the northern horizon. Choose a location with a clear, unobstructed view to the north, and expect the cluster to be dimmer and less steady than it would be at higher altitudes. If the cluster is too low to sketch comfortably, M52 may be a better target for a southern session, since it is observed in a different part of the sky.

For M52, plan your session for autumn evenings in the northern hemisphere, when Cassiopeia stands well placed. Observers in the southern hemisphere will find the cluster lower in the sky, and the timing will depend on their latitude.

Sketching technique for M38

Preparing your eyes and your equipment

Allow your eyes to dark-adapt for about 20 minutes before you begin. Avoid white light during this time. Use a dim red torch or a red-filtered headlamp to read your notes and adjust the telescope. Red light preserves your night vision better than white light does.

Use a low-power eyepiece to start. For a 70-90 mm refractor, magnifications of about 25x to 40x give a field several times wider than the cluster, so you can see the whole group and the stars around it. Check that the telescope is focused on a star before you begin, and refocus during the session as the air changes.

Prepare a sketch sheet with a circle drawn to match the field of view of your eyepiece. Mark north at the top, and note the eyepiece, magnification, aperture, date, time, and sky conditions. Keep a pencil and a soft eraser nearby, and use a clipboard or a flat surface that you can reach without moving your head.

Drawing the field

Start with the overall layout. Lightly mark the positions of the brightest stars in the cluster first, then fill in fainter ones. Work from the outside inwards for M38, so the irregular outline is correct before you add detail.

Use a small number of dot sizes to show brightness. Three or four sizes are usually enough: a large dot for the brightest stars, a medium dot for the next group, and small dots for the faintest. Use the same sizes throughout the drawing, so that the brightness levels stay consistent.

Draw only what you can confirm. If a star flickers in and out of view, mark it lightly or leave it out, and write a short note. A faint star that you see with averted vision can be drawn as a dot with a small question mark beside it.

For M38, the gaps between stars matter as much as the stars themselves. Check your sketch against the eyepiece by looking at both at intervals. If the spacing on paper looks very different from the spacing in the eyepiece, correct the drawing before you go further.

Recording details

Add the background star field only where it helps show the cluster's outline. If you draw too many background stars, the cluster will be harder to read. Note any haze or uneven sky brightness in the margin, since this explains why some stars were harder to see.

Plan on about 30 to 60 minutes for a careful sketch. Stop and rest your eyes if you find yourself drawing from memory rather than from the eyepiece.

What each target teaches

M38 teaches you to measure and draw spacing across a wide, scattered field. It rewards patience, because the faint members appear slowly as your eyes adjust, and it shows you how a loose group looks when the background is rich.

M52 teaches you to show density and gradual change in brightness. Its core asks you to decide how much detail to draw in a crowded area, and that decision carries over to other compact clusters.

Sketching both gives you a reference for judging open clusters in general. The skills you build on one target, such as dark adaptation, averted vision, and consistent dot sizes, apply directly to the other.