The sky around RCW 172, 3° across, north up NGC 6664 low-power eyepiece, 1° NE 1°
The sky around RCW 172 at true scale, north up and east left, with stars to magnitude 8. The circles show the field of a low-power eyepiece and of 10×50 binoculars.

RCW 172

Emission nebula (H II region) in Scutum

Emission nebula (H II region) in Scutum.

SCUTUM

The box shows where RCW 172 sits in Scutum.

Constellation
ScutumSct
Magnitude
-visual
Size
7′apparent
Distance
-light-years
Best month
Augustat 9 pm
Best with
Telescope

RCW 172 is an emission nebula (H II region) in Scutum

RCW 172 is an emission nebula (H II region) in the constellation Scutum. spans 7′. It is a telescope object, 6 inches or larger, and it is highest in the evening sky in August.

Nebula: a cloud of gas and dust. Emission nebulae glow on their own, lit by ultraviolet light from hot young stars; reflection nebulae shine by starlight scattered from dust; dark nebulae block the light behind them.

RCW 172 is RCW 172 in the RCW catalog of southern H-alpha regions

A. W. Rodgers, C. T. Campbell and J. B. Whiteoak listed it in their catalog of H-alpha emission regions in the southern Milky Way (1960), from photographs taken at Mount Stromlo Observatory.

Finding RCW 172 from η Ser

η Ser RCW 172 SCUTUM

RCW 172 lies 5.9° southeast of η Ser, the magnitude 3.2 star. Three fingers held at arm's length cover about 5°.

RCW 172 is highest in the evening in August

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 60°N JAN at 60°N: -33° high at 9 pm FEB at 60°N: -37° high at 9 pm MAR at 60°N: -33° high at 9 pm APR at 60°N: -22° high at 9 pm MAY at 60°N: -7° high at 9 pm JUN at 60°N: 7° high at 9 pm JUL at 60°N: 18° high at 9 pm AUG at 60°N: 23° high at 9 pm SEP at 60°N: 18° high at 9 pm OCT at 60°N: 8° high at 9 pm NOV at 60°N: -7° high at 9 pm DEC at 60°N: -21° high at 9 pm 50°N JAN at 50°N: -41° high at 9 pm FEB at 50°N: -47° high at 9 pm MAR at 50°N: -41° high at 9 pm APR at 50°N: -25° high at 9 pm MAY at 50°N: -7° high at 9 pm JUN at 50°N: 12° high at 9 pm JUL at 50°N: 26° high at 9 pm AUG at 50°N: 33° high at 9 pm SEP at 50°N: 27° high at 9 pm OCT at 50°N: 13° high at 9 pm NOV at 50°N: -6° high at 9 pm DEC at 50°N: -25° high at 9 pm 40°N JAN at 40°N: -48° high at 9 pm FEB at 40°N: -57° high at 9 pm MAR at 40°N: -49° high at 9 pm APR at 40°N: -28° high at 9 pm MAY at 40°N: -6° high at 9 pm JUN at 40°N: 17° high at 9 pm JUL at 40°N: 34° high at 9 pm AUG at 40°N: 43° high at 9 pm SEP at 40°N: 35° high at 9 pm OCT at 40°N: 18° high at 9 pm NOV at 40°N: -5° high at 9 pm DEC at 40°N: -27° high at 9 pm 30°N JAN at 30°N: -54° high at 9 pm FEB at 30°N: -67° high at 9 pm MAR at 30°N: -55° high at 9 pm APR at 30°N: -30° high at 9 pm MAY at 30°N: -5° high at 9 pm JUN at 30°N: 21° high at 9 pm JUL at 30°N: 42° high at 9 pm AUG at 30°N: 53° high at 9 pm SEP at 30°N: 43° high at 9 pm OCT at 30°N: 22° high at 9 pm NOV at 30°N: -4° high at 9 pm DEC at 30°N: -29° high at 9 pm 20°N JAN at 20°N: -59° high at 9 pm FEB at 20°N: -77° high at 9 pm MAR at 20°N: -60° high at 9 pm APR at 20°N: -31° high at 9 pm MAY at 20°N: -4° high at 9 pm JUN at 20°N: 24° high at 9 pm JUL at 20°N: 49° high at 9 pm AUG at 20°N: 63° high at 9 pm SEP at 20°N: 50° high at 9 pm OCT at 20°N: 25° high at 9 pm NOV at 20°N: -3° high at 9 pm DEC at 20°N: -30° high at 9 pm 10°N JAN at 10°N: -61° high at 9 pm FEB at 10°N: -87° high at 9 pm MAR at 10°N: -62° high at 9 pm APR at 10°N: -32° high at 9 pm MAY at 10°N: -3° high at 9 pm JUN at 10°N: 27° high at 9 pm JUL at 10°N: 54° high at 9 pm AUG at 10°N: 73° high at 9 pm SEP at 10°N: 55° high at 9 pm OCT at 10°N: 28° high at 9 pm NOV at 10°N: -1° high at 9 pm DEC at 10°N: -30° high at 9 pm 0° JAN at 0°: -60° high at 9 pm FEB at 0°: -82° high at 9 pm MAR at 0°: -61° high at 9 pm APR at 0°: -31° high at 9 pm MAY at 0°: -1° high at 9 pm JUN at 0°: 29° high at 9 pm JUL at 0°: 58° high at 9 pm AUG at 0°: 82° high at 9 pm SEP at 0°: 59° high at 9 pm OCT at 0°: 30° high at 9 pm NOV at 0°: -0° high at 9 pm DEC at 0°: -29° high at 9 pm 10°S JAN at 10°S: -56° high at 9 pm FEB at 10°S: -72° high at 9 pm MAR at 10°S: -57° high at 9 pm APR at 10°S: -29° high at 9 pm MAY at 10°S: 0° high at 9 pm JUN at 10°S: 30° high at 9 pm JUL at 10°S: 59° high at 9 pm AUG at 10°S: 87° high at 9 pm SEP at 10°S: 60° high at 9 pm OCT at 10°S: 31° high at 9 pm NOV at 10°S: 1° high at 9 pm DEC at 10°S: -27° high at 9 pm 20°S JAN at 20°S: -50° high at 9 pm FEB at 20°S: -63° high at 9 pm MAR at 20°S: -51° high at 9 pm APR at 20°S: -26° high at 9 pm MAY at 20°S: 1° high at 9 pm JUN at 20°S: 30° high at 9 pm JUL at 20°S: 57° high at 9 pm AUG at 20°S: 77° high at 9 pm SEP at 20°S: 58° high at 9 pm OCT at 20°S: 31° high at 9 pm NOV at 20°S: 2° high at 9 pm DEC at 20°S: -25° high at 9 pm 30°S JAN at 30°S: -43° high at 9 pm FEB at 30°S: -53° high at 9 pm MAR at 30°S: -44° high at 9 pm APR at 30°S: -22° high at 9 pm MAY at 30°S: 3° high at 9 pm JUN at 30°S: 29° high at 9 pm JUL at 30°S: 53° high at 9 pm AUG at 30°S: 67° high at 9 pm SEP at 30°S: 54° high at 9 pm OCT at 30°S: 30° high at 9 pm NOV at 30°S: 4° high at 9 pm DEC at 30°S: -21° high at 9 pm 40°S JAN at 40°S: -35° high at 9 pm FEB at 40°S: -43° high at 9 pm MAR at 40°S: -36° high at 9 pm APR at 40°S: -18° high at 9 pm MAY at 40°S: 4° high at 9 pm JUN at 40°S: 27° high at 9 pm JUL at 40°S: 47° high at 9 pm AUG at 40°S: 57° high at 9 pm SEP at 40°S: 48° high at 9 pm OCT at 40°S: 28° high at 9 pm NOV at 40°S: 5° high at 9 pm DEC at 40°S: -17° high at 9 pm below horizon low 20-40° 40-60° overhead-ish

The chart gives its height above the horizon at 9 pm through the year, from 60°N to 40°S. It can be seen from the whole southern hemisphere and north to about 83°N.

The distance to RCW 172 is not well measured

Objects within 6° of RCW 172

RCW 172 catalog data

FieldValue
Typeemission nebula (H II region)
ConstellationScutum
Right ascension (J2000)18h 36.5m
Declination (J2000)-07° 29′
Apparent size7′
Best monthAugust
Best withTelescope
RCW numberRCW 172