Finding and Sketching the Phantom Galaxy M74 by Star-Hop

Before you start

Plan the session for the months in the facts table. The galaxy is best seen in November and December, when Pisces is well placed in the evening sky. Check the altitude row for your latitude before you set up, because it affects how much atmosphere the light passes through and how much time you have on the target.

Altitude by latitude

From 35 degrees north, the galaxy reaches about 71 degrees altitude at its highest point. From 50 degrees north, the maximum is about 56 degrees. From 35 degrees south, it climbs only to about 39 degrees. Observers in the southern hemisphere will see it low in the northern part of the sky, so the view is more affected by haze, street lighting, and the horizon. Observe it as close to its highest point as you can, and allow extra time for the view to steady.

Dark adaptation and equipment

Allow 15 to 20 minutes of dark adaptation before you start. Keep a red torch or a dimmed red light for reading charts and writing notes, because white light resets your night vision.

A 200 to 300 mm Dobsonian, as listed in the facts, shows the galaxy as a clearly visible oval glow. From a suburban sky with a naked-eye limit around magnitude 5, expect a faint patch rather than detail in the spiral arms. A finder of about 50 mm aperture, or a 10x50 binocular for the star-hop, is useful for the early stages.

The star-hop route

The route uses three stages: a naked-eye starting point, a sweep of about 19 degrees to a bright star in Pisces, and a short final hop of about 1.3 degrees to the galaxy.

Step 1: Find the Great Square of Pegasus

Look for the Great Square of Pegasus, a large, nearly square shape of four stars of similar brightness. In autumn evenings it is high in the east to south-east sky, depending on your latitude and the time.

Identify the corner of the square that lies farthest east. Its Bayer name is Algenib. It is the starting point for the hop. The other corners are Markab, Scheat, and Alpheratz, but you do not need them for this route.

Step 2: Sweep east to Eta Piscium

From Algenib, move your view east along the same low declination, which is roughly level with the square's bottom edge. Cover about 19 degrees. A practical way to measure this is with your hand held at arm's length: a closed fist covers about 10 degrees, so cover roughly two fists.

Along this sweep you will pass through a region with few bright stars. Keep counting fist widths so you do not overshoot. The star you are aiming for is Eta Piscium, a star in the Circlet of Pisces, a small, curved chain of stars. Eta Piscium should be visible without optical aid from a suburban sky, which makes it a reliable marker.

If you use a binocular, centre Eta Piscium in the field. A 10x50 binocular has a field of about 6 degrees, so the star will sit comfortably in the view and you can check the faint stars around it against your chart.

Step 3: Settle onto the galaxy

Switch to your telescope's finder or a low-power eyepiece with a field of about 2 degrees. Centre Eta Piscium first. The Phantom Galaxy lies about 1.3 degrees from it, so it sits near the edge of the view. Move the telescope about 1 degree toward the east and slightly north, and watch the eyepiece as you do it.

Move slowly. The galaxy is faint, so you may see it for a moment only at the edge of the field before you centre it. When it appears, pause and let your eye settle before you confirm the view.

Confirming you have arrived

A faint star field can mislead you, so check the target before you start a sketch.

• Look for a glow, not a point. A star has a sharp, bright centre. The galaxy is a diffuse patch with no sharp centre. If the object looks like a point of light, you have found a star, not the galaxy.
• Use averted vision. Look slightly to one side of the glow. The patch often becomes easier to see when it is not in the centre of your eye's sensitive area. Move your gaze back and forth to test whether the glow remains.
• Check the size. At 9.9 by 9.3 arcminutes, the galaxy is about one-sixth of a degree across, roughly a third of the width of the full Moon. Compare the patch with the stars around it. It should look large and soft, not small and bright.
• Check the shape. The expected view is an oval glow. At higher magnification the outline may become less clear, so the shape is a more reliable check at low power.
• Confirm the position. The galaxy should be near Eta Piscium, roughly 1.3 degrees to the west of it. If the nearest star in your view is not Eta Piscium, go back to Step 2 and re-check the fist count.

If you cannot see the glow after a few minutes, return the telescope to Eta Piscium, wait for your eye to adapt again, and repeat the nudge. Do not increase the magnification as a first response, because a higher magnification makes a faint glow harder to see.

Sketching the galaxy

Sketching helps you see detail that a glance may miss. For this target, the sketch records the field, the faint glow, and the stars that set the scale.

Setting up the sketch

Use a sketchpad, a soft pencil, and a red-lit board. Draw a circle to represent the eyepiece field. Mark the field's size and the magnification you used, so the sketch can be repeated later.

Place Eta Piscium at the correct position in the circle. Then add the faint stars that are visible around it, using their relative brightness. Mark each star with a small dot, and use a larger dot for brighter stars. The stars give you a scale for the glow and a check that you are looking at the right region.

What to record

When the galaxy is centred, draw its outline as a soft-edged oval. Show the brighter central area as a denser shade and the outer edge as a lighter one. Do not draw sharp edges, because the outline is soft.

Note the following in the margin:

• The eyepiece and magnification used.
• The aperture of the telescope.
• The sky conditions, such as haze, clouds, or visible light from the horizon.
• Whether you used averted vision to see the glow.
• The time spent observing the target, and your estimate of dark adaptation.

Take 10 to 15 minutes for the sketch. A longer session often produces less detail, because your eye begins to tire. If you return to the galaxy later, repeat the same method so the sketches can be compared.