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Cosmic Challenge: Two Pairs


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Cosmic Challenge:
Two Pairs

 

May 2020

 

Phil Harrington

 

This month's suggested aperture range:

Giant Binoculars (≥ 70mm)

 

3- to 5-inch (76-127mm) telescopes

 

 

 

Target

Type

RA

DEC

Const.

Mag

Size

NGC 4284

Galaxy

12 20.2

+58 05.6

Ursa Major

14.3p

2.5'x1.1'

NGC 4290

Galaxy

12 20.8

+58 05.6

Ursa Major

12.7p

2.3'x1.5'

M40

Double star

12 22.2

+58 05.0

Ursa Major

9.5

50"

 

Most agree that the Messier catalog of deep-sky objects stands as the finest single compilation of star clusters, nebulae, and galaxies visible from the northern hemisphere. When it comes time to single out the finest of the list's 109 entries, however, we often have trouble agreeing. Is it the Orion Nebula, M42; the Great Globular Cluster, M13; or maybe the Ring Nebula, M57? So many choices! One thing is for certain -- you'll never find Messier's 40th entry on anyone's "finest" list.

 

Above: Evening star map. Credit: Map adapted from Star Watch by Phil Harrington

Above: Finder chart for this month's Cosmic Challenge.
Click on the chart to open a printable PDF version.

 

 

We all make mistakes, and M40 was one of Messier's. The story goes that in 1660, Johann Hevelius, a noted observer from Dantzig, Germany (now Gdansk, Poland) famous for his tubeless refractor, reported seeing a "nebula" near the star Megrez [Delta (δ) Ursae Majoris] . Five score and four years later, try as he might, Messier could not repeat Hevelius's observation. All he found were a pair of close-set 9th-magnitude stars. Messier noted on October 24, 1764: 

I searched for the nebula above the tail of the Great Bear, which is indicated in the [Hevelius] book Figure of the Stars, second edition...I have found, by means of this position, two stars very near to each other and of equal brightness, about the 9th magnitude, placed at the beginning of the tail of Ursa Major: one has difficulty to distinguish them with an ordinary [non-achromatic] refractor of 6 feet [focal length]. There is reason to presume that Hevelius mistook these two stars for a nebula. 

For reasons lost to history, Messier decided to include the pair in his catalog, even though he knew well that they were just two stars. 

 

Hevelius's legacy was resurrected again in 1863 when Friedrich Winnecke rediscovered the double star from Pulkovo Observatory in St. Petersburg, Russia. He marked down its position, and not knowing of the previous observations, subsequently included it as the fourth listing in his double star inventory, Doppelsternmessungen (Double Star Measurements). As a result, M40 is often cross listed as Winnecke 4. More recent observations based on data from the European Space Agency's astrometric satellite Hipparcos suggest that the two components may actually be just an optical alignment -- an optical double star -- not a true binary pair.

 

Call it M40 or Winnecke 4 as you prefer, we are looking at a pair of stars shining at magnitudes 9.65 and 10.10 and separated by about 53", and slowly widening. The brighter of the pair is a spectral type G0 sun, while other is a hotter F8 star. Both are resolvable through giant binoculars and, Messier's description to the contrary, offer little visual challenge for 3- to 5-inch apertures. Look for M40 about ½° northeast of 5.5-magnitude 70 Ursae Majoris, itself a degree northeast of Megrez.

 

Above: M40 (right), NGC 4290 (middle) and NGC 4284 (left) as seen through the author's 4-inch (102mm) refractor.

 

 

 

 

Above: Astrophotographer extraordinaire Steve Bellavia took this image of M40, NGC 4290, and NGC 4284, along with PGC 39934 and PGC 39827 from Mattituck, NY.

·         Equipment: Celestron 6-inch SCT, ZWO ASI 533MC Pro camera, and Astronomik L2 UV-IR cut-filter. 

·         Image Capture: 20 x 180 seconds

 

Although M40 leaves something to be desired, another object looms nearby that proves a worthy challenger for this size-class instrument. NGC 4290, a small barred-spiral galaxy, is just 11' to the west of M40. As portrayed in my sketch above, both easily fit into the same 85x field of my 4-inch (102mm) f/10 refractor, with NGC 4290 looking like a faint, perhaps slightly oval blur. The galaxy, rated at magnitude 11.8, is visible with difficulty through my refractor from my suburban backyard, but it is clear from darker sites.

 

If you have good luck with NGC 4290, then try to find an even fainter galaxy just to its west. Even under the darkest skies, NGC 4284 is a very difficult object through my 4-inch refractor-- and even larger telescopes. Shining at only magnitude 13.5, its presence is only whispered through my 6-inch (152mm) Schmidt-Cassegrain from a site where the NELM is slightly better than 6.0. As a visual clue that you are looking in the right place, NGC 4284 lies very near two 13th-magnitude field stars, one to its east, and the other to its south.

 

For those with apertures larger than the stated instrument range for this month's challenge -- a lot larger -- how about trying your luck with PGC 39934? You can just make it out in the photo above. PGC 39934 shines at 17th magnitude and measures a mere 0.6'x0.2' across. It has always eluded my 18-inch reflector, but you may do better.  If that was a little too tough, maybe give PGC 39827 a go.  You'll find it's 16th-magnitude disk about 4.5' west of 70 Ursae Majoris.  Use the photo to help find the way.

 

Good luck with this month's Cosmic Challenge! And be sure to post your results in this column's discussion forum.

 

Until next month, remember that half of the fun is the thrill of the chase. Game on!



About the Author:

Phil Harrington writes the monthly Binocular Universe column in Astronomy magazine and is the author of 9 books on astronomy.Visit www.philharrington.net to learn more.

 

A revised, second printing of Cosmic Challenge: The Ultimate Observing List for Amateurs is now available with updated data tables and charts for finding various solar system objects, such as Pluto and Vesta, as well as improved renditions of the many eyepiece sketches that accompany each of the 187 challenges encompassing more than 500 individual objects.The book is available from Amazon.com.  

Phil Harrington's Cosmic Challenge is copyright 2020 by Philip S. Harrington.All rights reserved.No reproduction, in whole or in part, beyond single copies for use by an individual, is permitted without written permission of the copyright holder.

 


  • Mark Strollo, John O'Hara and Knasal like this


8 Comments

Gave this a try last night with a 4.5" f/8 reflector from the edge of the Las Vegas Valley, notwithstanding the proximity of the moon.  It was an easy star hop from delta-UMa to M40, though with the bright background M40 wasn't readily visible at 25x.  Increasing magnification to 35x revealed M40, but not very distinctly.  The best view was at 75x, with the double star snapping into view as the eyepiece was focused.

 

The night before this I had looked at M51 and its companion with a 17.5" from the same location, and they were quite washed out, so I didn't even try for NGC 4290 visually last night with the 4.5".  I had seen NGC 4290 and NGC 4284 about a year ago from a dark location through a 16" SCT and had remarked that NGC 4284 was quite faint.

 

Last night I also was regaining familiarity with a Mallincam on a 6" f/4, and decided to see what result I got for the M40/NGC4290/NGC4284 field.  With a field of view roughly equivalent to that of the image by Steve Bellavia, I was pleased to see both galaxies clearly visible after a 60 second exposure.

    • PhilH likes this

Last night I also was regaining familiarity with a Mallincam on a 6" f/4, and decided to see what result I got for the M40/NGC4290/NGC4284 field.  With a field of view roughly equivalent to that of the image by Steve Bellavia, I was pleased to see both galaxies clearly visible after a 60 second exposure.

That's great!  How about sharing it here with the rest of us?  waytogo.gif
 

I was going to in past replies but I didn't see the usual way to post.  I tried again this month but got a message saying images are disabled for this community.  Did I miss something?

 

Actually went out last night and got the NGC objects in 20 seconds and the brighter PGC in 10 minutes (30 stacked 20 second subs).

 

Jay

    • PhilH likes this

I was going to in past replies but I didn't see the usual way to post.  I tried again this month but got a message saying images are disabled for this community.  Did I miss something?

 

Actually went out last night and got the NGC objects in 20 seconds and the brighter PGC in 10 minutes (30 stacked 20 second subs).

 

Jay

It would be great if you could share your results, Jay.  To do that, you'll first need to upload the images into your own CN Photo Gallery.  Once that's done, then you can share them in any forum that you want,  Just watch the file size restrictions.

Last night was clear, so I was able to attempt a challenge for once that wasn't smack dab in all my local light pollution. M40 was easy as can be, but try as I might I couldn't get the others to pop out. Looks like a trip to a darker site is in order for this one!

    • optinuke likes this

It would be great if you could share your results, Jay.  To do that, you'll first need to upload the images into your own CN Photo Gallery.  Once that's done, then you can share them in any forum that you want,  Just watch the file size restrictions.

Phil, thanks for the direction...the CN Photo Gallery is new to me.  I uploaded two images from May 2.

 

NGC4290SingleFrame20sec

This image is a single 20 second sub, oriented the same as Steve's image with south up.  Minimal processing was done.  The NGC objects are visible.

 

 

NGC4290BW10min

This is a stack of 30 subs to give 10 minutes total; more processing was done and color suppressed.

 

Looks like PGC 39827 was captured to the left of 70 UMa.  May 2nd's sky was even a little brighter than May 1st.  While these images won't earn any awards, I find it nice to be able to image under much less than ideal conditions.

 

For the record, these were taken with a Mallincam Skyraider 440DSC using a 6" f/4 imaging Newtonian with no coma corrector.

 

Jay

    • PhilH and RyanSem like this

I attempted to see the galaxies from my backyard at the edge of the Las Vegas Valley.  I made attempts with a 17.5" dob and a 16" SCT on different nights.  NGC 4290 was visible in both scopes, with the best views at 230x in the 17.5" and 270x in the 16", though still requiring averted vision.  No luck with NGC 2484 with either scope.  The two stars close to NGC 2484 were clearly visible, but I couldn't tease NGC 2484 out of the background skyglow. 

    • PhilH likes this

Phil, thanks for the direction...the CN Photo Gallery is new to me.  I uploaded two images from May 2.

Nice, Jay! Yup, you got them all. Thanks for sharing. 
 



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