You can use this map to help navigate your way from Altair in the Summer Triangle to the constellations Delphinus, Sagitta (suh-JIT-uh) and Brocchi’s Cluster. Only part of Aquila the Eagle is shown. The full constellation is shown in the map below. Maps created with Stellarium.
Sagitta the Arrow is one of those constellations few amateur astronomers pay much attention to. It’s dim, sparse and cowers in the radiance of the Summer Triangle, yet it’s shape is distinctive enough, like its neighbor Delphinus the Dolphin, that I thought it deserved spotlight treatment today.
The arrow goes back to Greek mythology and may have represented the one used by Zeus against a foe or perhaps by Heracles to kill a wayward eagle. It appears to be aimed right at Delphinus but I hardy think we want to spear the celestial dolphin. Let’s instead get familiar with Sagitta so that we can use it in the upcoming week to snag one of the brighter nebulas in the Milky Way.
This much wider map shows the entire southeastern sky at the end of twilight in late July, when the Summer Triangle dominates the view. Find Altair and then use the top map to make a beeline to Sagitta.
Sagitta is a small constellation like Delphinus, meaning you can completely cover it up with just three outstretched fingers. Go out around 10:30-11 p.m. and face southeast. Find Altair, the bottom-most star of the Summer Triangle, and look one fist to the left or east to spot Delphinus, which looks remarkably like a kite. Return to Altair and now look one fist above it to see the little arrow of four or five stars in a line. If you’re having trouble, bring out your binoculars for some optical enhancement.
Feel like going further? Take those binoculars and move one field above and a little to the right of the feathered end of the arrow. You’ll see one of the neatest asterisms in the sky called the "Coathanger" or Brocchi’s Cluster. Six stars form the bottom of the hanger while four others wrap around to make a hook. If the sky is really dark, you can even spot it with just your naked eye.
The Coathanger isn’t much use for hanging since it’s upside-down in the sky, and although it looks like a real star cluster, Brocchi’s just happens to be an attractive but chance alignment of stars.
No matter. We enjoy these gems whether they’re assembled properly or just thrown in the mix. Have at it.