If spring has been a mix of bad weather and low goals for you, as it has been for many of us, things are looking up as May rolls around. A total lunar eclipse highlights the list on May 15 and 16.
2022 total lunar eclipse
This eclipse favors the eastern part of North America and all of South America. Viewers on the west coast of North America will see the Moon rise with the eclipse in progress, while West Africa and Europe will see the Moon set before the eclipse ends . Check this site for the local circumstances of your eclipse.
If you’re on the west coast of North America and can’t set up your gear the night before, the rising moon will leave you with little chance of adjusting your exposure and focus, especially if you’re using a telescope. and want to capture a photo of the eclipsed Moon against the eastern horizon.
Be prepared to frame your exposures and use at least a single axis tracking mount. A tracker or astronomical mount will save you from having to adjust the pointing during the eclipse, which will last several hours. During the fully eclipsed portion of the event, you’ll also want to take exposures of up to a few seconds to capture the stars in the background as well. And by the way, even though the lunar eclipse is easily visible even in light-polluted cities, being able to see the stars in a dark place adds so much more to eclipse photos.
May also opened with a nice list of planets just before sunrise. Venus and Jupiter were close enough to be captured in a single image taken through a medium-sized telescope. As May progresses, Venus and Jupiter will separate, but all of the planets will still make a good widefield composition for a few weeks.
The usually active Lyrid meteor shower was largely a bust with the full moon limiting visibility, but the early morning Eta Aquariid meteor shower (Comet Halley dust) appears to be showing decent activity. Wikipedia lists the peak as occurring on May 6, but with activity actually extending from April 18 to May 28, we might as well be using our wide-field cameras whenever we shoot at night in May.
Distant, very distant galaxies
Spring is an in-between time for many astrophotographers, as the target-rich areas near the Milky Way galaxy set early in the evening or rise late in the morning. Since we are located towards the outer edge of our own galaxy, during this time we are looking in the opposite direction to the galactic core. We are thus able to see objects outside our galaxy without the interference of dust and gas. The downside is that these objects are very small, so a long camera lens or medium-sized telescope is the minimum starting point for astrophotography, and a tracking mount is a must.
At the shorter end of the gear range, all but a few galaxies will appear as more than fuzzy specks in the vast vacuum of space. But it is possible to photograph beautiful combinations of galaxies, such as the “Lion Trio”, so named because three galaxies (M65, M66 and NGC3628) can be photographed in a single shot. Even better, a camera modified for H-alpha sensitivity is not needed to see detail in galaxies.
Or try the Markarian Range, a beautiful arc of galaxies.
The Markarian Range is found in a relatively compact cluster of galaxies called the Virgo Cluster, located in the constellation Virgo, of course. Most galaxies will appear as fuzzy spots in small telescopes, but a few can be photographed in an astonishing variety of shapes, some actually interacting by gravity. The photo below was made on a medium format 6x7cm film, scanned and shown as a negative, which makes it a little easier to see the tiny galaxies. The Markarian Range is near the center of this plane.
The telescope used was a Borg 100ED (100mm aperture, f/4). The shot is from a single 45 minute exposure on Kodak PPF400 negative film (no longer available). I used the Millennium Star Atlas as a reference to hand label the galaxies on a rainy weekend. These days it’s easier to use Astrometry.Net to get a tagged photo. This site lets you upload an image and, after a few minutes, sends you back a graded version of your shot (among other info). Use a JPEG image and give the program some hints about where you were pointing to speed up its processing.
Find small weak targets
Photographing small, faint targets like galaxies brings a whole new set of challenges because you can’t see your target even in a wide-angle finderscope. The modern solution is to have computerized support. Ideally, if set up correctly (aligned with two or three stars on either side of the meridian), a reference bracket should point your scope at a target and have it in your camera’s field of view. In practice, especially when moving a great distance across the sky, a light mount may not be very accurate, so the best thing to do is to go to a bright, easily identifiable star nearby first to synchronize computer clocking. An older mount with analog setting circles would first need the same type of timing procedure on a nearby bright star.
Once the target is in the field of view, I turn the ISO on a DSLR or mirrorless camera to the maximum value and take a frame shot for a few seconds. This adjusts the pointing for better framing and gives me an idea of how long an exposure can be used when the ISO sensitivity is reduced to its best setting. As with all deep sky objects, multiple images will be required, so a camera intervalometer is required.
For advanced astrophotographers with very sophisticated setups (who don’t need to read this article), a fully computerized imaging camera, mount, and pointing software can move to the approximate target point, take an image, determine exactly where it is pointing (equivalent to using .net astrometry), and adjust the pointing so that the framing is exactly as specified by the user. But my own preference is not to use such a fancy (complicated) setup, especially for portable setups, so I use the procedures described earlier.
Whatever your preference, spring brings a whole new level of challenges for your astrophotography. Good shot!