May EAA Targets

 Summary  Easy: M67 and M104; Intermediate: Arp244 and M99; Difficult: Abell1656 and M97; Deep Southern: M83, NGC5128 and NGC2997.

 

Easy: M67  (8h 53m  / +11d 43'),  M104 (Sombrero galaxy) (12h 41m  / -11d 45') - Note: approximate JNOW co-ordinates.

 

 

M67
This old open cluster about 2700 light years distant in Cancer is visible in the West early in May, after it gets dark, and is an easy target for almost any set-up. M67 has about 500 members, and is one of the oldest open clusters in our galaxy, with a variety of stellar types including many similar to the sun and many red giants. Our view of the cluster from Earth is unobscured with minimal interstellar dust along the line of sight. Here is a monochrome 30sec capture with my AT130EDT reduced to f/5.5, and an ASI290MM mini, with ASILive at 300 gain:

 

M67 (ASI290MM mini /130EDT ); 2 x 15s

M104 (Sombrero galaxy)
Visible to the southeast after dark, the Sombrero galaxy, located at the border of Virgo and Corvus, is unmistakable in its resemblance to a sombrero, as the galaxy is viewed close to edge on with a dark dust lane bisecting its equatorial bulge.  M104 is slightly larger than the Milky Way and about 30 million light years distant. Although the galaxy should be easily visible, one challenge is to see if your view shows a slight narrowing of the dust lane, as one moves  from the eastern (left) end of the dust lane towards its middle/centre. This tapering is just about noticeable in the cropped/zoomed version of this capture. (Note: Taken a couple of nights ago with my new Player One Apollo-M Mini mono camera, using SharpCap 4.1 at 300 gain).

 

 

M104 (Sombrero galaxy, Apollo-M Mini/ 130EDT); 45 x 10s

M104 (Sombero galaxy, cropped/zoomed); 45 x 10s

A much harder challenge is to see if you can detect any structures or non-uniformities in the dark dust lane, some of which are visible in deep AP images of this target. However, since this target is in the “Easy” group, don’t worry if that dust lane doesn’t give up its secrets easily. 

Intermediate: Arp244 (NGC4038/4039) (Antennae Galaxies) (12h 03m  / -19d 00'), M99  (St. Catherine’s Wheel) (12h 20m  / +14d 17')

 

Arp244  (NGC4038/4039) (Antennae Galaxies)

This pretty pair of colliding galaxies - aptly named the Antennae Galaxies because of the long tidal tails created during the initial interaction of the pair - is located at about 65 million light years distant in Corvus, and visible towards the southeast after dark. Arp244 is one of the closest examples of such colliding galaxy pairs, and the central regions of both galaxies surrounding their cores are filled with young hot star clusters and bright star forming HII regions. They appear as bright knots in this slightly cropped 10minute capture, taken again with the 130EDT reduced to f/5.5 and my new Player One Apollo-M Mini mono camera, using SharpCap 4.1 at 300 gain:

 

             Arp244 (Antennae Galaxies, slight crop, Apollo-M Mini/ 130EDT); 60 x 10s

One challenge with the Antennae Galaxies is to trace the extent to which the antennae are visible; they are much fainter than the central regions of the galaxy pair. See, for example, if you can trace the southern antenna all the way to where it appear to end in a left/right (east/west) extension towards the lower right corner of the frame.

 

 

 

M99 (St. Catherine’s Wheel)

M99 is a very attractive spiral galaxy about 55 million light years away in Coma Berenices and visible towards the southeast after dark. This is one of the brighter spiral members of the Virgo cluster, and has two giant spiral arms. The giant spiral arm to the west (right) is somewhat elongated, as can be seen in this 6 minute capture taken with the 130EDT f/5.5 set-up:

 

M99 (St. Catherine’s Wheel, ASI290MM mini /130EDT); 24 x 15s

One challenge for M99 is to locate some of the many bright knots of HII regions  in the spiral arms. Longer exposures and sufficient image scale will help as this target is only about 5 arcminutes in apparent size.

Difficult: Abell1656 (Coma Cluster) (13h 01m  / +27d 51'), M97 (Owl Nebula) (11h 16m  / +54d 53')

 

 

Abell1656 (Coma Cluster)

 Abell1656, the Coma galaxy cluster, in Coma Berenices is visible in the east after dark. It contains over 1000 galaxies, covering over 2 degrees of the sky at a distance of over 300 million light years, and is one of the most prominent galaxy clusters. Most of the cluster members are ellipticals, including the two huge 13th magnitude galaxies, NGC2874 and NGC4889, at the centre of the cluster. Both are visible, surrounded by a swarm of smaller galaxies, at the centre of this 6 minute capture with the 130EDT @ f/5.5 / Apollo-M mini set-up from a couple of nights ago. 

 

 

Abell1656 (Coma Cluster, Apollo-M Mini/ 130EDT); 36 x 10s

As a challenge, consider counting how many galaxies are visible within 2 arcminutes of each of each of these two central ellipticals (NGC2874 and NGC4889); there are many! Interestingly, in Jan of this year a type Ia supernova was see in one of the galaxy members (NGC4850, near the middle of the right edge of the frame). It has faded subsequently, and I see no sign of it in the attached capture. (Don't worry, I'm not going to add detecting a faded supernova as part of this month's target list).

 

 

 

M97 (Owl Nebula)

M97 (the Owl Nebula) is a very distinctive planetary nebula, about 2000 light years away in Ursa Major, and approximately due north after dark at the beginning of the month. The distinctive eyes of the Owl correspond to two jets  of expelled matter moving in opposite directions, with the matter in the jets darkening the light of the expanding nebula. The Owl has an interesting internal structure discussed, for example, in Guerrero et al. It consists of a slightly elongated (from circular) double shell inner nebula, surrounded by a much fainter bow shaped outer halo. The double shell inner nebula is readily visible via EAA across a range of wavelengths, and the two inner shells are almost the same size. The outer halo, however,  exhibits an asymmetric bowman shape as the halo interacts with the interstellar medium in the direction the Owl nebula is moving.

 

One other interesting feature of the Owl is the prominent triangle of stars, including the central star (now a white dwarf), in the southern part of the Owl. These are readily visible, along with the two inner shells in this recent near 8 minute capture using my C8 reduced to f/3.7 (twin reducers) and a Player One Neptune-C II at 300 gain.(The innermost shell appears green in this view, surrounded by the fuzzy red of the second shell):

 

M97 (Owl Nebula, Neptune-C II /C8); 33 x 15s

Both inner shells also show up well in a pure H-alpha view, as in this 8 minute capture with a 7nm H-alpha filter and the 130EDT @ f/5.5 / Player One Apollo-M mini set-up:

 

 

M97 (Owl Nebula, H-alpha, Apollo-M Mini/ 130EDT); 16 x 30s

Anyone looking for the toughest challenge in this month’s selection is welcome to try and capture the faint asymmetric bow shaped outer halo of this planetary. I tried it a couple of nights ago with a 7nm OIII filter and my AT130EDT and ASI290MM mini using an ultrafast f/1.6 configuration, and watched the livestack for 30 minutes. I could see the brightest part of the outer halo start to appear after a few minutes towards the northeast, but even with extreme stretching the halo was barely noticeable above the sky background after 30 minutes. Here’s the cropped central part of a very grainy, extreme-stretch 30 minute capture that shows the asymmetric shape of the outer halo – narrower towards the northeast (upper left) and wider (and fainter) towards the southwest (lower right). It’s not pretty, but it’s viewable doing EAA. I think a fast scope and OIII narrowband or dual narrowband filter may do the trick for those who want to try this.

 

 

M97 (Owl Nebula, OIII, cropped, ASI290MM mini /130EDT) ; 60 x 30s

Another easier challenge is to locate some of the small background galaxies both north (e.g. PGC2490291 and PGC2490640), and south (PGC34279) of the Owl. These (and other) background galaxies are faintly visible in this unfiltered 6 minute capture of the Owl taken with the C8 @ f/3.7 and ASI290MM mini at 300 gain a few years ago.

 

M97 (Owl Nebula, ASI290MM mini /C8); 72 x 5s

Deep Southern: M83 (Southern Pinwheel Galaxy) (13h 38m  / -29d 59'), NGC5128 (Arp153)(Centaurus A) (13h 27m  / -43d 09') and NGC2997 (9h 47m / -31d 18m)

 

 

M83 (Southern Pinwheel Galaxy)

For northern observers this beautiful barred spiral in Hydra is still low in the southeast early in the month; higher in the sky later in the evening or for our southern hemisphere observers. M83 is a face-on barred spiral about 15 million light years distant, and it exhibits a lot of detail – knotty regions of star formation – in its spiral arms, as well as distinctive dust lanes in its disc. For a challenge, try to see the two tiny neighboring galaxies (PGC48132 and PGC724525) a little due east (left) of the outer spiral arm. These are visible in this 9 minute capture of M83 taken with the 130EDT at its native f/7 on a night of decent seeing. 

 

 

M83 (Southern Pinwheel Galaxy, ASI290MM mini /130EDT); 36 x 15s

NGC5128 (Arp153) (Centaurus A)

This fascinating radio galaxy located far south about 12 million light years away in Centaurus barely culminates at a little over 13 degrees at my location in early May a bit after midnight. So for many northern observers, this target may not be accessible. However, for anyone that can see it, Centaurus A is the 5th brightest galaxy in the sky, with a distinctive “twisted” dust lane bisecting the galaxy.  A supermassive black hole lies at its centre, powering two relativistic jets that are the source of both radio and X-ray emissions. Although the jets are beyond the reach of EAA, some amateurs doing AP (e.g. Rolf Olsen) have captured parts of them. As an EAA challenge for this target, try and see how much of the central dust lane you can make out. This 7 minute capture with 130EDT @ f/7.0 /Apollo-M Mini set-up shows part of the lane silhouetted against the galactic bulge.

 

NGC5128 (Centaurus A, Apollo-M Mini /130EDT); 28 x 15s

NGC2997

This pretty spiral galaxy in Antlia is about 40 million light years away and is the brightest member of a group of galaxies (the NGC2997 group). As it is just west of south after dark at the beginning of May, for northern observers it is best observed early in the month. As the galaxy is inclined to our line of sight it has an oval shape with prominent spiral arms and dust lanes. The spiral arms have knots of star forming HII regions throughout. One challenge is to see the almost 90 degree “kink” in the western (right) arm located at about 3-4pm relative to the nucleus. That kink shows up in these two 10 minute captures (one with the  C8 @ f/3.7 / Neptune-C II set-up, and the other with the 130EDT @ f/5.5 /ASI290MM mini set-up, both at 300 gain):

 

 

NGC2997 (Neptune-C II /C8); 40 x 15s

NGC2997 (ASI290MM mini /130EDT); 40 x 15s

Many of these targets are seasonal favourites that are not new to those who have been doing EAA for a while. Hopefully, at least one or two targets may offer a bit of a challenge to both old and new hands alike. For myself, I usually don’t spend a lot of time on planetaries, but had a fun time with the Owl and its surroundings. If I had not included the Owl,  I doubt I would have had that experience.

 

Clear skies to us all!