Sky & Telescope - December 2020 - 22

Catalog Celebration

GLOBULAR CLUSTERS Start
high in the west-southwestern
sky with the tiny constellation
Delphinus, the Dolphin, off the
"nose" of Pegasus. Here you'll
find two of the most northerly
globular clusters in the Caldwell
Catalog, C42 (NGC 7006) and
C47 (NGC 6934). C42 is the
dimmer of the two globulars, at
least as seen from Earth, and
with good reason: At 135,000
light-years, it lies more than
two-and-a-half times as far
away as C47, well beyond the
disk of the Milky Way.
C47

observer. One evening in 1995 he was struck by the fact that
many worthy deep-sky objects were either never observed by
Messier, or at least not included in his catalogs. As Moore
wrote in the foreword to Stephen James O'Meara's Deep-Sky
Companions: The Caldwell Objects, ". . . there are many other
objects of equal or greater interest than those with 'M' designations. Many of these non-Messier sights are shamefully
neglected . . . . Why not draw up a catalog to list objects not
identified by Messier?"
The next morning Moore wrote up a list of 109 deep-sky
objects spread across the entire sky, including challenges for
those with large telescopes. He decided to arrange his list by
declination, so that observers could quickly zero in on the
most southerly (or northerly) objects available to them, and
get an accurate tally of how many were within their reach.
Since the 'M' designation was already taken by the Messier
catalog, Moore invoked his full last name, Caldwell-Moore,
called his list the Caldwell Catalog, and assigned 'C' numbers
to the objects. Then, as he wrote, "Having completed my list,
I put it in an envelope and sent it off to Sky & Telescope. To be
candid, I thought very little more about it. Creating the list

PLANETARY NEBULAE A large swath of
the western sky offers no fewer than five
Caldwell planetary nebulae. Start in the
northwest with C6, the Cat's Eye Nebula
(NGC 6543), in Draco, just about halfway
between Delta and Zeta Draconis. A little
more than 20° to the southeast, in the western wing of Cygnus, the Swan, you'll find
C15, the Blinking Planetary (NGC 6826).
Another sweep almost twice as
much farther east takes you to
Andromeda and C22, the Blue
Snowball (NGC 7662), flying
near the zenith on late-autumn
evenings. Now pivot south and
C22
swoop down low to Aquarius to

had been an interesting exercise, but would anyone else be
interested in it?"
The editors at Sky & Telescope were indeed interested.
Thanks to the widespread availability of Dobsonian reflectors and affordable Schmidt-Cassegrains, interest in deepsky observing had been increasing since the 1970s. Moore's
new list of deep-sky objects, chosen for their visual splendor
and astrophysical significance, and composed for a global
audience, seemed certain to capture readers' attention. As
former editor in chief Rick Fienberg explains, "He [Moore]
sent us his letter and list of objects and said we could do
with it as we please. We responded by asking him to write
an article explaining his rationale for compiling the list
and for ordering it by declination from north to south.
He responded by saying he was too busy to write such an
article, but that we were welcome to adapt his letter for
an article ourselves. That's why Barlow Pepin is the coauthor [in the December 1995 issue] - he was the editor
assigned to turn what Patrick sent us into an article. Patrick
approved the article before we published it and was thrilled
at how it came out."

find C55, the Saturn Nebula (NGC 7009).
The planetaries listed so far are small, but
with high surface brightness, so they hold
up surprisingly well under moderate light
pollution if you use high magnification. But
you'll want the opposite - dark skies and
low magnification - to pick up the fifth and
final Caldwell planetary on this tour: C63,
the Helix Nebula (NGC 7293). The large
apparent size and low surface
brightness of the Helix are due to
its proximity: At a little more than
500 light-years away, it's much
closer than the other planetaries listed here, which range from
1,400 to 3,200 light-years away.
C6

22

DECEMBER 2 02 0 * SK Y & TELESCOPE

C 42 & 47: ESA / HUBBLE / N ASA; C22: M ASIL IM AGING TE A M; C6: NORDIC
OPTICA L TELESCOPE / RO M A NO CORR A DI / ISA AC NE W TON G ROUP OF
TELESCOPES, SPAIN

C42



Sky & Telescope - December 2020

Table of Contents for the Digital Edition of Sky & Telescope - December 2020

Contents
Sky & Telescope - December 2020 - Cover1
Sky & Telescope - December 2020 - Cover2
Sky & Telescope - December 2020 - 1
Sky & Telescope - December 2020 - Contents
Sky & Telescope - December 2020 - 3
Sky & Telescope - December 2020 - 4
Sky & Telescope - December 2020 - 5
Sky & Telescope - December 2020 - 6
Sky & Telescope - December 2020 - 7
Sky & Telescope - December 2020 - 8
Sky & Telescope - December 2020 - 9
Sky & Telescope - December 2020 - 10
Sky & Telescope - December 2020 - 11
Sky & Telescope - December 2020 - 12
Sky & Telescope - December 2020 - 13
Sky & Telescope - December 2020 - 14
Sky & Telescope - December 2020 - 15
Sky & Telescope - December 2020 - 16
Sky & Telescope - December 2020 - 17
Sky & Telescope - December 2020 - 18
Sky & Telescope - December 2020 - 19
Sky & Telescope - December 2020 - 20
Sky & Telescope - December 2020 - 21
Sky & Telescope - December 2020 - 22
Sky & Telescope - December 2020 - 23
Sky & Telescope - December 2020 - 24
Sky & Telescope - December 2020 - 25
Sky & Telescope - December 2020 - 26
Sky & Telescope - December 2020 - 27
Sky & Telescope - December 2020 - 28
Sky & Telescope - December 2020 - 29
Sky & Telescope - December 2020 - 30
Sky & Telescope - December 2020 - 31
Sky & Telescope - December 2020 - 32
Sky & Telescope - December 2020 - 33
Sky & Telescope - December 2020 - 34
Sky & Telescope - December 2020 - 35
Sky & Telescope - December 2020 - 36
Sky & Telescope - December 2020 - 37
Sky & Telescope - December 2020 - 38
Sky & Telescope - December 2020 - 39
Sky & Telescope - December 2020 - 40
Sky & Telescope - December 2020 - 41
Sky & Telescope - December 2020 - 42
Sky & Telescope - December 2020 - 43
Sky & Telescope - December 2020 - 44
Sky & Telescope - December 2020 - 45
Sky & Telescope - December 2020 - 46
Sky & Telescope - December 2020 - 47
Sky & Telescope - December 2020 - 48
Sky & Telescope - December 2020 - 49
Sky & Telescope - December 2020 - 50
Sky & Telescope - December 2020 - 51
Sky & Telescope - December 2020 - 52
Sky & Telescope - December 2020 - 53
Sky & Telescope - December 2020 - 54
Sky & Telescope - December 2020 - 55
Sky & Telescope - December 2020 - 56
Sky & Telescope - December 2020 - 57
Sky & Telescope - December 2020 - 58
Sky & Telescope - December 2020 - 59
Sky & Telescope - December 2020 - 60
Sky & Telescope - December 2020 - 61
Sky & Telescope - December 2020 - 62
Sky & Telescope - December 2020 - 63
Sky & Telescope - December 2020 - 64
Sky & Telescope - December 2020 - 65
Sky & Telescope - December 2020 - 66
Sky & Telescope - December 2020 - 67
Sky & Telescope - December 2020 - 68
Sky & Telescope - December 2020 - 69
Sky & Telescope - December 2020 - 70
Sky & Telescope - December 2020 - 71
Sky & Telescope - December 2020 - 72
Sky & Telescope - December 2020 - 73
Sky & Telescope - December 2020 - 74
Sky & Telescope - December 2020 - 75
Sky & Telescope - December 2020 - 76
Sky & Telescope - December 2020 - 77
Sky & Telescope - December 2020 - 78
Sky & Telescope - December 2020 - 79
Sky & Telescope - December 2020 - 80
Sky & Telescope - December 2020 - 81
Sky & Telescope - December 2020 - 82
Sky & Telescope - December 2020 - 83
Sky & Telescope - December 2020 - 84
Sky & Telescope - December 2020 - Cover3
Sky & Telescope - December 2020 - Cover4
https://www.nxtbook.com/nxtbooks/aas/st_202112
https://www.nxtbook.com/nxtbooks/aas/st_202111
https://www.nxtbook.com/nxtbooks/aas/st_202110
https://www.nxtbook.com/nxtbooks/aas/st_202109
https://www.nxtbook.com/nxtbooks/aas/st_202108
https://www.nxtbook.com/nxtbooks/aas/st_202107
https://www.nxtbook.com/nxtbooks/aas/st_202106
https://www.nxtbook.com/nxtbooks/aas/st_202105
https://www.nxtbook.com/nxtbooks/aas/st_202104
https://www.nxtbook.com/nxtbooks/aas/st_202103
https://www.nxtbook.com/nxtbooks/aas/st_202102
https://www.nxtbook.com/nxtbooks/aas/st_202101
https://www.nxtbook.com/nxtbooks/aas/skywatch_2021
https://www.nxtbook.com/nxtbooks/aas/st_202012
https://www.nxtbook.com/nxtbooks/aas/st_202011
https://www.nxtbook.com/nxtbooks/aas/st_202010
https://www.nxtbook.com/nxtbooks/aas/st_202009
https://www.nxtbook.com/nxtbooks/aas/st_202008
https://www.nxtbook.com/nxtbooks/aas/st_202007
https://www.nxtbook.com/nxtbooks/aas/st_202006
https://www.nxtbook.com/nxtbooks/aas/st_202005
https://www.nxtbook.com/nxtbooks/aas/st_202004
https://www.nxtbook.com/nxtbooks/aas/st_202003
https://www.nxtbook.com/nxtbooks/aas/st_202002
https://www.nxtbook.com/nxtbooks/aas/st_202001
https://www.nxtbook.com/nxtbooks/aas/st_201912
https://www.nxtbook.com/nxtbooks/aas/st_201911
https://www.nxtbook.com/nxtbooks/aas/st_201910
https://www.nxtbook.com/nxtbooks/aas/st_201909
https://www.nxtbook.com/nxtbooks/aas/st_201908
https://www.nxtbook.com/nxtbooks/aas/st_201907
https://www.nxtbook.com/nxtbooks/aas/st_201906
https://www.nxtbook.com/nxtbooks/aas/st_201905
https://www.nxtbook.com/nxtbooks/aas/st_201904
https://www.nxtbook.com/nxtbooks/aas/st_201903
https://www.nxtbook.com/nxtbooks/aas/st_201902
https://www.nxtbook.com/nxtbooks/aas/st_201901
https://www.nxtbook.com/nxtbooks/aas/st_201812
https://www.nxtbook.com/nxtbooks/aas/st_201811
https://www.nxtbook.com/nxtbooks/aas/st_201810
https://www.nxtbook.com/nxtbooks/aas/st_201809
https://www.nxtbook.com/nxtbooks/aas/st_201808
https://www.nxtbook.com/nxtbooks/aas/st_201807
https://www.nxtbook.com/nxtbooks/aas/st_201806
https://www.nxtbook.com/nxtbooks/aas/st_201805
https://www.nxtbook.com/nxtbooks/aas/st_201804
https://www.nxtbook.com/nxtbooks/aas/st_201803
https://www.nxtbook.com/nxtbooks/aas/st_201802
https://www.nxtbook.com/nxtbooks/aas/st_201801
https://www.nxtbook.com/nxtbooks/aas/st_201712
https://www.nxtbook.com/nxtbooks/aas/st_201711
https://www.nxtbook.com/nxtbooks/aas/st_201710
https://www.nxtbook.com/nxtbooks/aas/st_201709
https://www.nxtbook.com/nxtbooks/aas/st_201708
https://www.nxtbook.com/nxtbooks/aas/st_201707
https://www.nxtbook.com/nxtbooks/aas/st_201706
https://www.nxtbook.com/nxtbooks/aas/st_201705
https://www.nxtbook.com/nxtbooks/aas/st_201704
https://www.nxtbook.com/nxtbooks/aas/st_201703
https://www.nxtbook.com/nxtbooks/aas/st_201702
https://www.nxtbook.com/nxtbooks/aas/st_201701
https://www.nxtbook.com/nxtbooks/aas/st_201612
https://www.nxtbook.com/nxtbooks/aas/st_201611
https://www.nxtbook.com/nxtbooks/newtrack/st_201612
https://www.nxtbook.com/nxtbooks/aas/st_201610
https://www.nxtbook.com/nxtbooks/aas/st_201609
https://www.nxtbook.com/nxtbooks/aas/st_201608
https://www.nxtbook.com/nxtbooks/aas/st_201607
https://www.nxtbook.com/nxtbooks/aas/st_201606
https://www.nxtbook.com/nxtbooks/aas/st_201605
https://www.nxtbook.com/nxtbooks/aas/st_201604
https://www.nxtbook.com/nxtbooks/aas/st_201603
https://www.nxtbook.com/nxtbooks/aas/st_201602
https://www.nxtbook.com/nxtbooks/aas/st_201601
https://www.nxtbook.com/nxtbooks/aas/st_201512
https://www.nxtbook.com/nxtbooks/aas/st_201511
https://www.nxtbook.com/nxtbooks/aas/st_201510
https://www.nxtbook.com/nxtbooks/aas/st_201509
https://www.nxtbook.com/nxtbooks/aas/st_201508
https://www.nxtbook.com/nxtbooks/aas/st_201507
https://www.nxtbook.com/nxtbooks/aas/st_201506
https://www.nxtbook.com/nxtbooks/aas/st_201505
https://www.nxtbook.com/nxtbooks/aas/st_201504
https://www.nxtbook.com/nxtbooks/aas/st_201503
https://www.nxtbook.com/nxtbooks/aas/st_201502
https://www.nxtbook.com/nxtbooks/aas/st_201501
https://www.nxtbook.com/nxtbooks/aas/st_201412
https://www.nxtbook.com/nxtbooks/aas/st_201411
https://www.nxtbook.com/nxtbooks/aas/st_201410
https://www.nxtbook.com/nxtbooks/aas/st_201409
https://www.nxtbook.com/nxtbooks/aas/st_201408
https://www.nxtbook.com/nxtbooks/aas/st_201407
https://www.nxtbook.com/nxtbooks/aas/st_201406
https://www.nxtbook.com/nxtbooks/aas/st_mars
https://www.nxtbook.com/nxtbooks/aas/st_201405
https://www.nxtbook.com/nxtbooks/aas/st_201404
https://www.nxtbook.com/nxtbooks/aas/st_201403
https://www.nxtbook.com/nxtbooks/aas/st_201402
https://www.nxtbook.com/nxtbooks/aas/st_201401
https://www.nxtbook.com/nxtbooks/aas/st_201312
https://www.nxtbook.com/nxtbooks/aas/st_201311
https://www.nxtbook.com/nxtbooks/aas/st_201310
https://www.nxtbook.com/nxtbooks/aas/st_201309
https://www.nxtbook.com/nxtbooks/aas/st_201308
https://www.nxtbook.com/nxtbooks/aas/st_201307
https://www.nxtbook.com/nxtbooks/aas/st_201306
https://www.nxtbook.com/nxtbooks/aas/st_201305
https://www.nxtbook.com/nxtbooks/aas/st_201304
https://www.nxtbook.com/nxtbooks/aas/st_201303
https://www.nxtbook.com/nxtbooks/aas/st_201302
https://www.nxtbook.com/nxtbooks/aas/st_201301
https://www.nxtbook.com/nxtbooks/aas/st_201212
https://www.nxtbook.com/nxtbooks/aas/st_201211
https://www.nxtbook.com/nxtbooks/aas/st_201210
https://www.nxtbook.com/nxtbooks/aas/st_201209
https://www.nxtbook.com/nxtbooks/aas/st_201208
https://www.nxtbook.com/nxtbooks/aas/st_201207
https://www.nxtbook.com/nxtbooks/aas/st_201206
https://www.nxtbook.com/nxtbooks/aas/st_201205
https://www.nxtbook.com/nxtbooks/aas/st_201204
https://www.nxtbook.com/nxtbooks/aas/st_201203
https://www.nxtbook.com/nxtbooks/aas/st_201202
https://www.nxtbook.com/nxtbooks/aas/st_201201
https://www.nxtbook.com/nxtbooks/aas/st_201112
https://www.nxtbook.com/nxtbooks/aas/st_201111
https://www.nxtbook.com/nxtbooks/aas/st_201110
https://www.nxtbook.com/nxtbooks/aas/st_201109
https://www.nxtbook.com/nxtbooks/aas/st_201108
https://www.nxtbook.com/nxtbooks/aas/st_201107
https://www.nxtbook.com/nxtbooks/aas/st_201106
https://www.nxtbook.com/nxtbooks/aas/st_201105
https://www.nxtbook.com/nxtbooks/aas/st_201104
https://www.nxtbook.com/nxtbooks/aas/st_201103
https://www.nxtbook.com/nxtbooks/aas/st_201102
https://www.nxtbook.com/nxtbooks/aas/st_201101
https://www.nxtbook.com/nxtbooks/aas/st_201012
https://www.nxtbook.com/nxtbooks/aas/st_201011
https://www.nxtbook.com/nxtbooks/aas/st_201010
https://www.nxtbook.com/nxtbooks/aas/st_201009
https://www.nxtbook.com/nxtbooks/aas/st_201008
https://www.nxtbook.com/nxtbooks/aas/st_201007
https://www.nxtbook.com/nxtbooks/aas/st_201006
https://www.nxtbook.com/nxtbooks/aas/st_201005
https://www.nxtbook.com/nxtbooks/aas/st_201004
https://www.nxtbook.com/nxtbooks/aas/st_201003
https://www.nxtbook.com/nxtbooks/aas/st_201002
https://www.nxtbook.com/nxtbooks/aas/st_201001
https://www.nxtbookmedia.com