Cahill Rooftop Observatory

Suggested Targets

The Moon

The Moon can look spectacular, although you will need to use the polarizing filters to cut down the brightness to bearable levels. Lunar features look best at quarter phase, when sunlight hits them at a low angle and casts long shadows. You can find lists of good features on S&T's Moon page.


The major planets – Venus, Mars, Jupiter, Saturn – make for excellent visual and CCD targets. RDRO observers have spotted the phases of Venus, moons and bands of Jupiter, and rings and moons of Saturn. Some have claimed to have also seen the Martian polar caps. Uranus and Neptune, while much less impressive, are visible as well. The locations of the planets can be determined most readily from Sky & Telescope's Sky at a Glance page, or from the hard copy S&T in the library (which should be borrowed for only as long as it takes to xerox, not for a night's observing run).

The S&T website has dozens of other useful tools, including:

Mercury has not been reported in the RDRO observing logs, but should be readily visible at certain times.


The IAU Minor Planet Center maintains a complete list of cometary ephemerides, although many of these will be far beyond the capabilities of our telescopes. This list is incorporated into Starry Night's database as part of its update process.

If there's a good comet around, it will likely be featured on S&T's Sky at a Glance page or its comets page.


S&T lists the best asteroids at any given time on its asteroid observing page. True to their name, though, even the "best" asteroids still look like stars!

The IAU Minor Planet Center maintains a complete list of asteroid ephemerides and look up tools. Starry Night regularly updates its own asteroid data as well.

Earth Orbit

The International Space Station, Hubble Space Telescope, and Space Shuttle are some of the brightest satellites in low Earth orbit. S&T has a calculator that can predict when these three satellites will be visible. For other satellites, or more detailed predictions such as finder charts, your best resource is Heavens Above. Heavens Above can also predict Iridium flares, but you'll have to give your position to within a few miles – just saying "Los Angeles" won't cut it.

Double/Multiple Stars

η [eta] Cas00h 49.1m+57° 49′3.5, 7.2yellow, purple13″
Almachγ [gam] And02h 03.9m+42° 20′2.1, 4.8yellow, greenish-blue10″
ι [iot] Cas02h 29.1m+67° 24′4.5, 6.9, 8.4yellow, blue-white, blue-white3″, 7″
32 Eri03h 54.3m-02° 57′4.7, 5.9yellow, blue-green7″
Rigelβ [bet] Ori05h 14.7m-08° 12′0.1, 6.8blue, white10″
26 Aur05h 38.6m+30° 30′6.0, 6.3, 8.0yellow, blue, ?12″
σ [sig] Ori05h 38.7m-02° 36′3.7, 6.3, 6.7, 8.8yellow, blue-white, orange11″, 13″, 43″
γ [gam] Lep05h 44.5m-22° 27′3.6, 6.3yellow, red96″
ε [eps] Mon06h 23.8m+04°36′4.5, 6.5gold, blue13″
β [bet] Mon06h 28.8m-07° 02′4.7, 5.2, 6.2yellow-white7″, 3″
12 Lyn06h 46.2m+59° 27′5.4, 6.0, 7.32″, 9″
145 CMa07h 16.6m-23° 19′4.8, 6.0yellow, blue27″
Castorα [alf] Gem07h 34.6m+31° 53′2.0, 2.9white, yellow-white4″
Tegmenζ [zet] Cnc08h 12.2m+17° 39′5.6, 6.0, 6.3yellow-white, yellow-orange6″
ι [iot] Cnc08h 46.7m+28° 46′4.0, 6.6orange, blue31″
HD 8102909h 23.3m+03° 30′7.3, 8.3white, gray21″
Algiebaγ [gam] Leo10h 20.0m+19° 51′2.6, 3.8orange, greenish4″
54 Leo10h 55.6m+24° 45′4.3, 6.3green-white, blue?7″
Alula Borealisν [nu] UMa11h 18.5m+33° 06′3.5, 9.97″
65 UMa11h 55.1m+46° 29′6.5, 7.0, 8.3yellow-white63″, 4″
24 Com12h 35.1m+18° 23′5.1, 6.3orange, green20″
Cor Caroliα [alf] CVn12h 56.0m+38° 19′2.9, 5.6yellow-white, pale blue?20″Colors less well-defined than Albireo.
Mizarζ [zet] UMa13h 23.9m+54° 56′2.2, 3.9white15″
Izarε [eps] Boo14h 45.0m+27° 04′2.3, 4.5yellow, bluish3″
ν [nu] Boo15h 30.9m+40° 50′5.0, 5.0blue-white, red628″Nice wide binary.
ζ [zet] CrB15h 39.4m+36° 38′5.0, 6.0white, blue6″
ξ [xi] Sco16h 04.4m-11° 22′4.8, 7.3white, gray8″
Akrabβ [bet] Sco16h 05.4m-19° 48′2.6, 4.9blue, white14″
Jabbahν [nu] Sco16h 12.0m-19° 28′4.4, 5.4, 6.7, 7.8yellow, orange, ?, ?1″, 41″, 2″Easy to find, but colorless.
Rasalgethiα [alf] Her17h 14.6m+14° 23′3.1-3.9, 5.4orange, bluish-green5″
95 Her18h 01.5m+21° 36′5.0, 5.2green, red6″Nice close pair.
70 Oph18h 05.5m+02° 30′4.0, 6.0yellow, red4″
Albireoβ [bet] Cyg19h 30.7m+27° 58′3.1, 5.1gold, blue34″Classic double star.
ο1 [omi] Cyg20h 13.6m+46° 44′3.8, 4.8, 7.0338″, 107″
Algediα [alf] Cap20h 18.1m-12° 33′3.6, 4.2yellow378″
γ [gam] Del20h 46.7m+16° 07′4.3, 5.1yellow, blue-green10″Nice close pair
61 Cyg21h 06.9m+38° 45′5.2, 6.0yellow-orange28″
δ [del] Cep22h 29.2m+58° 25′4.1, 6.3orange, blue41″Nearby stars provide a nice contrast.
σ [sig] Cas23h 59.0m+55° 45′5.0, 7.1blue, green3″

Open Clusters

Open clusters are a safe target on hazy nights because they're not extended sources. The individual stars are less sensitive to light pollution than nebulosity or unresolved starlight would be.

Double ClusterNGC 86902h 19.0m+57° 09′4.330′
Double ClusterNGC 88402h 22.4m+57° 07′4.430′
M 3402h 41.1m+42° 45′5.235′
PleiadesM 4503h 47.0m+24° 07′1.51.8°Good Questar target, too sparse for other telescopes.
M 3705h 52.3m+32° 33′5.624′
M 3506h 08.9m+24° 21′5.128′
M 4106h 46.0m-20° 45′4.538′
Praesepe, Beehive ClusterM 4408h 40.4m+19° 40′3.11.3°Rich field. Best spring cluster.
M 6708h 51.4m+11° 49′6.930′
M 2317h 56.9m-19° 01′5.527′
Small Saggitarius Star CloudM 2418h 17.4m-18° 36′4.61.5°
M 2518h 31.7m-19° 07′4.632′Bright, compact cluster. Some members clearly red or blue.
Wild Duck ClusterM 1118h 51.1m-6° 16′6.314′Rich, but faint. Barely visible in the C-8, clearer in C-14.

Globular Clusters

Globular clusters can look quite nice on a clear night, and make spectacular CCD targets.

NGC 414712h 10.1m+18° 32′10.34′
M 5313h 12.9m+18° 10′7.713′
M 313h 42.2m+28° 23′6.318′
NGC 546614h 05.5m+28° 32′9.111′
M 515h 18.6m+02° 05′5.723′
Hercules ClusterM 1316h 41.7m+36° 28′5.820′Most accessible globular cluster from Pasadena.
M 7119h 53.8m+18° 47′8.47′
M 1521h 30.0m+12° 10′6.318′Faint, but visible.
M 221h 33.5m-00° 49′6.616′


Crab NebulaM 1SNR05h 34.5m+22° 01′8.46′Invisible in even the C-14 eyepiece. Great CCD target, though.
Orion NebulaM 42H II05h 35.4m-05° 27′3.71.1°Easily visible even on hazy nights.
Eskimo NebulaNGC 2392PN07h 29.2m+20° 55′9.20.7′
Ghost of JupiterNGC 3242PN10h 24.8m-18° 38′7.80.6′
Cat's Eye NebulaNGC 6543PN17h 58.6m+66° 38′8.10.3′Easy to see, but no detail.
Lagoon NebulaM 8H II18h 03.8m+24° 23′4.61.5°Barely discernible in the C-14 on a good night. Nice cluster, though.
Omega/Horseshoe/Swan NebulaM 17H II18h 21.1m-16° 11′6
Ring NebulaM 57PN18h 53.6m+33° 02′8.81.4′Clear ring even in hazy weather
Dumbbell NebulaM 27PN19h 59.6m+22° 43′7.36′Visible in C-14, but hard to see structure.
Saturn NebulaNGC 7009PN21h 04.2m-11° 22′80.4′Easy to see, but no detail.
Blue SnowballNGC 7662PN23h 25.9m+42° 32′92.2′


Andromeda GalaxyM 31S00h 42.7m+41° 16′3.53×1°
Sculptor FilamentNGC 253S00h 47.6m-25° 17′7.125×7′
NGC 2903S09h 32.2m+21° 30′913×7′
Bode's GalaxyM 81S09h 55.6m+69° 04′6.921×10′
Cigar GalaxyM 82S(p)09h 55.8m+69° 41′8.49×4′
M 95SB10h 44.0m+11° 42′9.74×3′
M 96S10h 46.8m+11° 49′9.26×4′
M 105E10h 47.8m+12° 35′9.32′
M 65S11h 18.9m+13° 05′9.38×1.5′
M 66S(p)11h 20.2m+12° 59′98×3′
NGC 3628S(p)11h 20.3m+13° 36′9.514×4′
3C 273QSO12h 29.1m+02° 03′12.7
M 49E12h 29.8m+8° 00′8.48′
Virgo GalaxyM 87E12h 30.8m+12° 24′8.67′
Sombrero GalaxyM 104S12h 40.0m-11° 37′89×4′
M 94S12h 50.9m+41° 07′8.27×3′
Black Eye GalaxyM 64S(p)12h 56.7m+21° 41′8.59×5′
Whirlpool GalaxyM 51S(p)13h 29.9m+47° 12′8.48′

Alignment Stars

The following list of easy-to-find stars will be useful for calibrating a telescope's setting circles or GO-TO system. All of the stars listed here are on the C-14's Bright Star List, accessible from Objects->Strs or from within the Star-Sync or 2-Star calibration routines.

AlpheratzAndromeda-Pegasus border00h 08m 23s+29° 05′ 26″
MirfakFollow Andromeda northeast to a bright star03h 24m 19s+49° 51′ 40″
AldebaranThe "V" northwest of Orion04h 35m 55s+16° 30′ 34″
Capella05h 16m 41s+45° 59′ 53″
BetelgeuseNortheast shoulder of Orion05h 55m 10s+07° 24′ 25″
Alphard09h 27m 35s-08° 39′ 31″
RegulusBottom of the sickle of Leo10h 08m 22s+11° 58′ 02″
Spica13h 25m 12s-11° 09′ 41″
AlkaidTip of Big Dipper's handle13h 47m 42s+49° 18′ 48″
ArcturusFollow Big Dipper's handle to a bright, isolated star14h 15m 40s+19° 10′ 57″
Rasalhague17h 34m 56s+12° 33′ 36″
VegaWesternmost star in Summer Triangle18h 36m 56s+38° 47′ 01″
NunkiNortheast tip of "teapot's" handle18h 55m 16s-26° 17′ 48″
AltairSouthernmost star in Summer Triangle19h 50m 47s+08° 52′ 06″
DenebShort end of Cygnus, northeast star in Summer Triangle20h 41m 26s+45° 16′ 49″
FomalhautBright star in south in October-December22h 57m 39s-29° 37′ 20″

Color Calibrators

Anyone who wants to do "true-color" astrophotography needs to worry about color balance. To human vision, sunlight appears white, so solar twins serve as an excellent white-light standard to set the relative scaling of the red, green, and blue frames.

StarRADecV Mag
HIP 99600h 12m 28.3s+20° 14′ 04″8.2
HIP 289400h 36m 43.4s+48° 49′ 42″8.7
HD 620401h 02m 57.4s-09° 51′ 40″8.6
HD 1119501h 49m 42.9s-18° 56′ 10″8.9
HD 1226402h 00m 05.3s-13° 32′ 46″8.0
HD 1563202h 31m 24.2s+22° 05′ 15″8.0
HIP 1191502h 33m 49.0s-19° 36′ 43″8.9
HIP 1461403h 08m 44.3s+15° 20′ 05″7.8
HD 2455203h 54m 22.6s+01° 15′ 42″8.0
HD 3615205h 28m 59.1s-17° 25′ 45″8.3
HD 5971107h 30m 40.0s-15° 59′ 41″7.7
HD 6348707h 48m 06.0s-27° 31′ 11″9.2
HIP 4131708h 25m 49.5s-29° 55′ 50″7.8
HD 7700609h 01m 37.0s+49° 44′ 13″7.9
HIP 4493509h 09m 10.3s+10° 49′ 18″8.7
HD 7866009h 09m 53.9s+14° 27′ 24″8.3
HIP 4957210h 07m 10.2s+29° 27′ 23″9.3
HIP 4975610h 09m 23.4s+02° 22′ 16″7.6
HD 9190910h 37m 59.6s+54° 53′ 14″9.2
HD 9207410h 39m 05.9s+55° 30′ 45″8.6
HIP 5540911h 20m 51.8s-23° 13′ 02″8.0
HD 9861811h 21m 29.1s+58° 29′ 04″7.7
HIP 6415013h 08m 51.0s+05° 12′ 26″6.8
HD 11516913h 15m 47.4s-29° 30′ 21″9.2
HIP 6479413h 16m 48.4s+12° 24′ 56″8.4
HD 11573913h 19m 17.7s-15° 34′ 03″8.9
HIP 7381515h 05m 13.2s+06° 17′ 24″8.2
HD 13490215h 11m 37.1s+24° 13′ 58″8.9
HD 13815915h 30m 25.2s-01° 19′ 08″9.2
HD 14233115h 54m 19.8s-08° 34′ 49″8.8
HIP 8819418h 00m 38.9s+29° 34′ 19″7.1
HIP 10096320h 28m 11.8s+22° 07′ 44″7.1
HIP 10215220h 41m 54.6s-27° 12′ 57″9.2
HD 20956222h 04m 49.7s-23° 43′ 46″8.9
HIP 10993122h 15m 54.7s+24° 55′ 41″8.9