Telescope Reviews: Lim Mag Charts of M44 -- LINK

This Chart is still in progress. I have not labeled any of the magnitudes. However, some information about the population of stars in m44 gives a very good indication of magnitude ranges.

M44 has 80 stars to mag 10.0 and has 100 stars to mag 10.9. This chart has just over 200 stars plotted, 140+ stars plotted within the boundary and 60 more within the 2° square periphery. I can see every star on this chart when tested with my 5" scope that has a measured LM of 13.1, so this chart reaches to about mag 13.

Can you see single stars resolved in M44?
The 25 brightest stars all range between mag 6.3 to mag 8.0. There are a number of close pairings that would result in naked eye integrated magnitudes potentially bright enough to see as "resolved stars". While the brightest single star in M44 is 6.3, these 4 pairs all result in brighter naked eye integrated magnitudes. They would be seen as 5.8, 5.9, 6.0 and 6.1. These include all the stars in M44 brighter than mag 6.6. So after these 4 groups that have integrated magnitudes, seeing a "5th star" puts you at NELM 6.6. There are several other pairs that are not as close as 3 arcmin but more like 5-6 arcmin.

The chart has now been edited to include only those stars around this cluster that I have been viewing, even though they are outside the cluster boundary. My starting point guide post is the bright pair at upper right just outside the true boundary. On the west there is a very distinct N-S line of 5 bright stars, running almost from top to bottom of the cluster. On the south there is a distinct string of mostly bright stars just outside the true boundary that I use as my defining limits. On the left (the east) there is a very noticable barren area that helps clearly define that edge.

Here are results from recent observations over a two night period. Both nights were about mag 4.9. These recent observations overlooked 4-6 stars on the extreme periphery that were included in all the earlier observations, so all of these counts in this first group are slightly lower than the history, but these here are all comparable to each other.
39 stars - Oberwerk Mariner 7x50 (actually measures only 7x43)
39 stars - Captain's Storm King 7x50(old single coated Swift)
41 stars - William Optic 7x50
42 stars - Captain's Helmsman 7x50
40 stars - Bushnell Legend 8x42 roof
40 stars - Nikon AE 8x40
48 stars - Nikon AE 10x50
51 stars - Nikon AE 12x50
57 stars - Fujinon FMT-SX 10x50
88 stars – Oberwerk Ultra 15x70

If I were to hazard a guess, I'd say 40 stars is mag 9 and 50 stars is about mag 9.6 to 9.8. In all cases, each of these binoculars saw just a few stars on the limit borderline needing averted vision.

Here's the history - best readings from the more complete and careful observations. With various binoculars I have seen
56 stars using Pentax PCF WP 10x50 sky5.2
57 stars using Fujinon FMT-SX 10x50 sky4.7
64 stars using Oberwerk Mariner 10x60 sky5.2
67 stars using Fujinon 10x70 sky5.2
72 stars using Nikon Superior E 12x50 sky5.2
70 stars using Orion Minigiant 15x63 sky5.0
80 stars using Oberwerk 15x70 sky5.0
90 stars using Fujinon 16x70 sky5.0
97 stars using Fujinon 16x70 sky5.3
94 stars using Burgess LW 20x80 sky5.0
82 stars using Celestron Giant 20x80 sky4.7
99 stars using Anttler Optic 18.5x80 sky4.9
101 stars using Anttler 18.5x80 sky mag5.0
116 stars using Garrett 21x80 sky mag5.0
the above observations fall probably just below mag 11.

103 stars using Fujinon 16x70 sky5.5
102 stars with Oberwerk 24xBT100 (26mm Meade SP LP)sky4.8
117 stars with Oberwerk 25xBT100 (24.8mm stock WA ep)sky5.2
123 stars using Oberwerk 25x100 IF sky5.2
These observations probably reach mag 11.3 to 11.4

128 stars with Garrett 21x80 triplet IF sky5.6
127 stars with Oberwerk 25x100 IF sky5.2
125 stars with Oberwerk 25xBT100 (24.8mm stock WA ep)sky5.6
135 stars with Oberwerk 24xBT100 (26mm Meade SP LP) sky5.6
these observations probably range from mag 11.5 close to mag12

And finally these higher powered observations
135 stars with Oberwerk 31xBT100 (20mm TV plossls)sky5.0
150 stars with Oberwerk 44xBT100 (14mm Radians)sky5.2
174 stars with Oberwerk 44xBT100 (14mm Radians)sky5.5
this last observation probably reaches close to mag12.5
(+ clouds interfered)

edit. this observation added 11-11-05
166 stars seen with Oberwerk 25x100 IF sky 5.6-5.8
This observation is singled out for several reasons.
this reading is 30 stars more than I had ever seen before at 25x100
I awoke at 3:30-4:00 AM and went outside, completely dark adapted
Temp was 34°, but the binoculars had been out from the night before
the sky had very good transparency, no moisture in the air
I easily found M101 this night. There are not many times I've seen M101.
M44 was bright naked eye and looked grainy, ?suspect resolved a few?
This observation includes several stars that were not seen in the BT100 at 44x.
I think this 25x100 binocular observation reaches close to mag 12.5

Take this chart out with you and circle all the stars you can see.
80 stars within the boundary = you've reached mag 10.0
over 100 stars within the boundary = you've gone beyond mag 10.9
140-150 stars on the chart and you are at about mag 12

The smallest symbol on the chart designates all the stars I have not yet see even with 44x100. The next smallest symbol represents all the remaining faint stars that were not seen with any binocular below the 44x100. (except that quite a few were seen with the Oberwerk 25x100 on 11-11-05)

M44 Chart of stars to mag13

edit
I have in my hands a draft observation sheet marked up from an observation on Feb 06 with my C5 (5" SCT) at 150x. On that night, (nothing special as far a NELM is concerned, about 5.2-5.4), I observed over 230 stars in and around M44. There were a few stars observed that are not plotted on this chart. I have not yet edited the master chart. But rest assured, you are not going to see all of those with a binocular, I doubt even at 40x100. FWIW, adding these few extra would take these charts potentially just a little deeper than mag 13.

edz

Post Extras