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Notes for object NGC 2403

28 note(s) found in NED.

1. 2011AJ....141...23B
Re:NGC 2403
A.3. NGC 2403
Another member of the M81 group, NGC 2403, is a late-type
spiral galaxy located at a distance of 3.2 Mpc. It has previously
been studied by Thilker et al. (1998) and by Mashchenko et al.
(1999) using an automated object recognition package who
detected 50 and 601 holes, respectively. Even though this galaxy
is highly inclined (i = 62.9^deg^), its close proximity and good
resolution allowed us to detect 173 holes in its HI distribution.
A few supershells were detected but the majority (81%) of the
holes are smaller than 350 pc in diameter and younger than
20 Myr. There are also several special cases: some of the holes
are most likely a superposition of two or more holes (hole
number 51, 157, and 173); holes number 10 and 43 have a
peculiar signature in pV space.

2. 2009A&A...503..409H
Re:NGC 2403
There is a faint polarized component which is predominantly diffuse, but is too
faint to characterize well with the current observations. Smoothing to a beam
size of 45" x 45" enhances the signal to noise ratio of some of the polarized
emission, which is concentrated in the western half of the galaxy, with some
localized enhancements at the eastern and western edges of the optical disk. But
even after application of smoothing, it is still extremely faint (typical
surface brightness ~30-50 microJy/beam, reaching as high as ~100 microJy/beam).
The lowest brightness of polarized emission occurs on the receding major axis
(PA = 125^deg^, as tabulated in Table 1). Deeper observations would be required
to further constrain the magnetic field properties in this target. The three
unresolved polarized sources which are detected in the field do not permit a
good estimation of the Galactic foreground RM in view of their large scatter.

3. 2008AJ....136.2648D
Re:NGC 2403
4.3 - NGC 2403 is a late-type Sc spiral and member of the M81 group. Its H I
rotation curve has been derived in many previous studies. The first measurement
using a synthesis telescope was presented in Shostak (1973). NGC 2403 has since
been re-observed and re-analyzed at ever-increasing sensitivity and resolution
by, among others, Bosma (1978), Begeman (1987), Sicking (1997), and Fraternali
et al. (2002). In Figure 7 we compare our curve with some of these analyses, all
corrected to the same distance. There is generally good agreement between the
various determinations. Beyond ~13 kpc the curves differ somewhat, but most of
the velocity information at these radii originates from close to the minor axis
of the velocity field, and thus depends on details such as the weighting used in
the tilted ring fit and the flux limit used to mask the velocity field.
Other parameters also compare favorably: the average i and P.A. values found
by Begeman (1987) were 60.2^deg^ and 122.5^deg^, respectively. Sicking (1997)
found 60.9^deg^ and 123.9^deg^, whereas Fraternali et al. (2002) derived
62.9^deg^ and 124.5^deg^. Our average values (defined as the average
unweighted values of the model distributions) agree well, at 62.9^deg^ and
123.7^deg^, respectively. Similarly, the average absolute difference between our
V_sys_ value and the three literature values is only 0.5 km s^-1^. The "bump" at
R ~ 15 kpc in the THINGS curve is real, in the sense that it cannot be explained
by an incorrectly chosen i or P.A. Most of the information in this part of the
curve originates from the two arms that are seen to stretch away in the
outermost northern and southern parts of the H I map. Motions along these arms
could explain the feature, as suggested by the kinks in the velocity contours at
those radii. The velocity fields of NGC 2403 are also discussed in Section 3.2.

4. 2008AJ....136.2648D
Re:NGC 2403
6.2. NGC 2403 -Figure 24 shows the surface brightness profiles derived from the
3.6 {mu}m data, as well as the 2MASS J, H, and K profiles. The 3.6 {mu}m profile
can be reliably traced to ~430" galactocentric radius, and the 2MASS profiles
out to ~380". The (J - K) color shows a clear trend, from ~0.9 in the inner
parts to ~0.6 at the outermost measured radii. This translates into a trend of
{GAMMA}^3.6^_*_ ~= 0.6 in the center to an outer {GAMMA}^3.6^_*_ ~= 0.3. Beyond
the radius where (J - K) (and therefore {GAMMA}^3.6^_*_) could be reliably
determined we assume a constant value {GAMMA}^3.6^_*_ = 0.3. The surface
brightness profile shows evidence for a second component in the inner parts.
Based on its rather modest appearance, it is not clear though whether this
constitutes a dynamically separate component. We therefore considered both
cases. For the single-component case, we simply multiplied the surface
brightness profile with the derived {GAMMA}^3.6^_*_ values. For the double-
component case, we decomposed the profile in two exponential profiles. The outer
component is described by a central surface brightness {mu}^3.6^_0_ = 16.9 mag
arcsec^-2^ and a scale length h = 1.81 kpc. The inner component has {mu}^3.6^_0_
= 16.7 mag arcsec^-2^ and h = 0.41 kpc. We used the fitted model as a
description for the inner disk. For the outer disk, we used the observed surface
brightness distribution, with the inner disk model subtracted. We extended the
observed outer disk profile with the corresponding fit at large radii where the
disk was no longer directly observable. The (J - K) color shows a slight
increase in the inner parts. For the inner disk, we therefore assumed a constant
value of {GAMMA}^3.6^_*_ = 0.6, whereas for the outer, main disk we assumed the
single-disk color distribution, the only difference being that we adopted a
constant {GAMMA}^3.6^_*_ = 0.5 for the innermost (R < 40") parts. Figures 25 and
26 present the fits for the single and multiple disk models, respectively. The
NFW models (fixed and free) are of the same quality as the free ISO model. The
fixed {GAMMA}^3.6^_*_ ISO models are of a somewhat lower quality. NGC 2403 in
combination with the ISO model prefers higher {GAMMA}^3.6^_*_ values than
predicted from the infrared color.

5. 2007MNRAS.382.1552L
Re:NGC 2403
NGC 2403: The nuclear cluster (labelled source 1) is apparent in Fig. 2. It is
just resolved in our images and completely resolved in HST images (Drissen et
al. 1999). The B/I image shows that the cluster is redder than the average
colour of the cirumnuclear regions. The two bright knots to the east of the
nucleus are found to be extended objects in the AO imaging of Davidge & Courteau
(2002). They suggest that these objects could be blends of two or more stars, or
compact star clusters. Spectra of the nucleus and one of the extended sources
(source 2) were obtained and can be seen in Fig. 2. Both show absorption
features and very weak nebular emission lines. Our spectral analysis shows that
both sources present very similar star formation histories. No radio or
point-like X-ray emission is observed at the nucleus position (Turner & Ho 1994;
Fraternali et al. 2002).

6. 2007ApJS..173..538T
Re:NGC 2403
NGC 2403 (Fig. 16.32).-Often compared to M33, this SAB(s)cd H II galaxy
satisfies both our criteria for being considered an XUV-disk. The outermost XUV
disk complexes lie near local maxima within the H I filament, which begins near
the northwest end of the major axis and wraps counterclockwise around the north
side of the galaxy (Fraternali et al. 2002). In at least one case, there appears
to be an H I shell surrounding the XUV complex (at 07^h^34^m^47.5^s^,
+65{degree}41'29"), highlighting the feedback of outer disk star formation on
the gas morphology. The combination of NGC 2403's large angular extent
(projecting background galaxies onto the XUV disk) and proximity (breaking up
complexes) makes it difficult to tell the difference between isolated XUV clumps
and background sources seen through the most rarified portions of the H I disk.
Gas accretion has been suggested as the origin of extraplanar H I (Fraternali &
Binney 2006) in this object. Known or likely companions include NGC 2366 (NOG
catalog), DDO 44 (KK61), Holmberg II, UGC 04483, and K52 (Karachentsev
1994; Karachentsev et al. 2000). NGC 2403 may be an outlier galaxy within the
M81 group.

7. 2006MNRAS.366.1265B
Re:NGC 2403
This SABc galaxy shows amorphous spiral features. The H{alpha} velocity maps and
the PV diagram show an almost rigid structure near the centre of the galaxy.
Bright H II regions can be seen in the H{alpha} monochromatic image. It is not
clear whether this galaxy is barred or not. According to Schoenmakers, Franx &
de Zeeuw (1997), their Fourier harmonic analysis of the H I velocity field shows
that non-circular motions are not important in this galaxy. Moreover, Schaap,
Sancisi & Swaters (2000) stress that the thin hydrogen disc of NGC 2403 is
surrounded by a vertically extended layer of H I that rotates slower than the
disc. A complete modelling of the galaxy will provide more details on its
structures. Fraternali et al. (2001) suggest that this anomalous H I component
may be similar to a class of high-velocity clouds observed in the Milky Way. In
CO data, no molecular gas is detected (Helfer et al. 2003).

8. 2005MNRAS.360.1201H
Re:NGC 2403
NGC 2403. This SABc galaxy shows amorphous spiral features. The H{alpha}
velocity maps and the PV diagram show an almost rigid structure near the centre
of the galaxy. Bright H II regions can be seen in the H{alpha} monochromatic
image. It is not clear whether this galaxy in barred or not. According to
Schoenmakers et al. (1997), their Fourier harmonic analysis of the H I velocity
field shows that non-circular motions are not important in this galaxy.
Moreover, Schaap et al. (2000) stress that the thin hydrogen disc of NGC 2403 is
surrounded by a vertically extended layer of H I that rotates slower than the
disc. A complete modelling of the galaxy will provide more details on its
structures. Fraternali et al. (2001) suggest that this anomalous H i component
may be similar to a class of HVCs observed in the Milky Way. In CO data, no
molecular gas is detected (Helfer et al. 2003).

9. 2005ApJS..157...59L
Re:NGC 2403
NGC 2403 is a Sc galaxy with open spiral arms at a distance of 3.133 Mpc. ULX1
is on the amorphous spiral arms.

10. 2002ApJS..140..303L
Re:NGC 2403
NGC 2403 (Fig. 30).-This spectrum is typical for a population with
numerous hot supergiants, which are responsible for the P Cyg profile
in Si IV. Other lines such as O VI, N V, and C IV are all consistent.
Photospheric Si III {lambda}1417, C III 1426, and S V {lambda}1501
from late-O stars are clearly detected. Apparently, the HUT spectrum
includes several bright HII regions in the spiral arm of NGC 2403. An
equivalent age of t = 20 Myr is derived. This age is very well
constrained by the strength and shape of C IV. A significant B
supergiant component is evident from the complex continuum longward of

11. 2002ApJ...573..306E
Re:NGC 2403
NGC 2403
A contour map of the radio sources in NGC 2403 can be seen in
Figure 6. We detected 15 sources with a signal-to-noise ratio of
5{sigma} or greater. Turner & Ho (1994) report 6 cm radio
observations of NGC 2403, including seven sources whose positions
lie within 1"-5" of a corresponding source found in our 20 cm map.
However, spectral index calculations were not possible since none
of the mutually observed sources had the same beam size and none
were unresolved. Examination of integrated fluxes reveals that
source {beta} is consistent with thermal emission.
A map of H II regions from Sivan et al. (1990) superimposed
onto our radio map reveals that {beta} lies directly over a group of
H II regions (including No. 293 in Sivan et al. 1990). Source {beta}
is likely a group of H II regions. The same positional coincidence
with a radio source and an H II region(s) is found for sources
{gamma}, {delta}, {epsilon}, {rho}, {theta}, {omega}, {eta}, {chi}
and {xi}. They are likely H II regions as well. We find that the
luminosities of these sources are comparable to H II regions
identified in Cowan et al. (1994).
Comparison with reported SNRs in NGC 2403 by Matonick & Fesen
(1997) reveals that source {mu} has a
peak position very close to that of SNRs 6 and 7. At a distance of
3.2 Mpc to NGC 2403 (see Table 2), {mu} is about 50 pc from both
SNRs 6 and 7. Since SNR 7 has a reported diameter of 60 pc, it is
very possible that is {mu} identified with this SNR. More radio
observations are recommended to confirm this identification.

12. 2002AJ....124..675C
Re:UGC 03918
Very extended radio source. Flux density from Condon (1987).

13. 2000MNRAS.319...17L
Re:NGC 2403
NGC 2403: This galaxy was observed with the Einstein HRI and IPC
instruments (Fabbiano & Trinchieri 1987). Three prominent sources were
identified in the IPC observations, with no emission from the nuclear
region of the galaxy.
The ROSAT HRI observations reported here show a total of four point
sources associated with the galaxy. Sources X1 and X3 in Fig. 10 correspond
to two of the sources reported by Fabbiano & Trinchieri (1987) (their third
source lies outside the JKT image). Sources X2 and X4 are about one order
of magnitude fainter than X1 and X3, and were probably below the
sensitivity threshold of the Einstein observations. It is confirmed that no
nuclear source is present in the galaxy, and a 2{sigma} upper limit for a
nuclear point source is given in Table 5.
A search for SNRs in NGC 2403 has yielded 35 detections (Matonick et al.
1997). The position of remnant number 15 in Table 2 of Matonick et al. is
coincident with the X-ray source X3 reported here (see Table 4). A very
faint optical counterpart is observed at this position. If the
identification is correct, the SNR would belong to a class of superluminous
(probably young) remnants (Schlegel 1994c).
Source X4 is coincident with a giant H II region. A photometric study
of this region (N2403-A) reveals more than 1400 detected stars, among them
800 O-type stars and a lower limit of 23 Wolf-Rayer stars (Drissen & Roy
The coincidence of X3 and X4 with previously known sources in NGC 2403
gives support to the astrometric checks carried out for this galaxy
(Section 3.2.2).

14. 1999ApJ...519...89C
Re:NGC 2403
NGC 2403.-NGC 2403 is a nearby spiral galaxy with similar global
properties to M33 (Thornley 1996). The galaxy has many H II regions, but
the nucleus seems quiescent (Beckman et al. 1987). A compact X-ray
source we found was near (offset = 17.1") but not coincident with the
galaxy nucleus.

15. 1999A&AS..136...35S
Re:NGC 2403
NGC 2403 -- Drissen & Roy (1996) detect broad He II {lambda}4686 and
C IV {lambda}5808 in two giant HII regions in this galaxy of the M 81

16. 1998PASJ...50..427S
Re:NGC 2403
NGC 2403: This Sc galaxy has a morphology similar to the nearby Sc
galaxy M33, showing amorphous spiral features. The PV diagram shows an
almost rigid-body rotation at R < 50", with a larger gradient in the
central +/- 10". The rotation curve is similar to that of M33. The disk
rotation is almost flat, but it still appears to gradually increase
toward the observed edge. The H{alpha}-to-[N II] line intensity ratio
(HNR) is as large as ~ 5 at the nucleus, slightly larger than the normal
value of about three for the H II regions.

17. 1997AstL...23..656G
Re:NGC 2403
NGC 2403. Sandage (1984b) (photographic photometry). Not all of the brightest
blue stars were photometered by Zickgraf and Humphreys (1991), apparently
because of plate overexposure. The corresponding LF is shifted to fainter
magnitudes by 0.4^m^ (Fig. 1c, dashed line).

18. 1997AstL...23..644G
Re:NGC 2403
NGC 2403. Van den Bergh (1992) (a recommendation that is based on an analysis
of the studies of other authors); Sandage (1984b) (nos. 165, 156, 57), (no.
189, V38, no. 159). The magnitudes and colors of the stars were determined by
Sandage (1984b). The magnitude scale was confirmed by Zickgraf and Humphreys
(1991), who photometered only a small number of bright stars due to plate

19. 1997AJ....114.2428S
Re:NGC 2403
NGC 2403: This is an Sc galaxy with open spiral arms, morphologically similar
to M33. The nuclear PV diagram shows a steep rise, reaching V_rot_~170 km s^-1^
within the central 10" (160 pc). Although the morphology is similar. the
nuclear rotation is different from that for M33.

20. 1996ApJS..103...81C
Re:NGC 2403
NGC 2403.--VLA B-configuration map showing compact radio components at 4.885
GHz in Turner & Ho (1994).

21. 1996ApJ...469L..45T
Re:NGC 2403
NGC 2403.--NGC 2403 is a nearby (3.2 Mpc) Scd galaxy with similar global
properties to the Local Group spiral M33. The NIR residual structure in
NGC 2403 is relatively uncertain because of its low surface brightness and
minimal bulge, but a two-arm spiral structure is marginally detected (see
Table 2), extending over as much as 180^deg^ in azimuth to a radius of ~2 kpc
(0.2 R_25_). The stronger, outer ridges of the spiral structure are also
consistent with enhanced star formation at the radius at which the gas surface
density in the disk becomes supercritical for star formation (Thornley & Wilson

22. 1994CAG1..B...0000S
Re:NGC 2403
Hubble Atlas, p. 36
Nov 6/7, 1950
30 min
The stellar content of NGC 2403, including
its brightest stars, the HII regions, the bright
irregular blue variables, and the Cepheids
require a distance modulus of m - M = 27.6
(Tammann and Sandage 1968). This value was
confirmed in a modern study by Freedman and
Madore (1988).
The brightest blue stars begin to resolve at
B = 18; the brightest red supergiants begin at
V = 19.5 (Sandage 1984b). NGC 2403 was the
first galaxy beyond the Local Group in which
Cepheid variables were found. It was the first
step in taking the distance scale outward into the
true expansion field. The large difference in the
distance modulus obtained from Cepheids of
m - M = 27.6, compared with Hubble and Humason's
(1931) value of m - M = 24.0, was a major
correction that eventually led to a stretching of
Hubble's original scale at large distances by a
factor of slightly more than ten, giving the global
value of the Hubble constant as near H = 50 km/s

23. 1993ApJS...86....5K
Re:NGC 2403
NGC 2403; Sc.
The flux of this galaxy is approximately constant through the ultraviolet
region. This normal Sc galaxy of the M 81 group is the prototypical
flocculent spiral (Elmegreen 1981), based on the disjoint nature of its
individual arms. NGC 2403 contains a large number of H II regions and OB
associations that are similar in size and distribution to those in M33
and in the LMC (Hodge 1985). The more active star formation regions of
NGC 2403 are not in the nucleus (Beckman et al. 1987), which appears

24. 1976RC2...C...0000d
Re:NGC 2403
In the M81 Group.
NGC 2404 [is a superassociation at 07h32m18.0s, +65d43m22s].
Ann. Ap., 28, 698, 1965 = Publ. O.H.P., 7, No. 50, P.A.S.P., 78, 495, 1966.
P.A.S.P., 84, 844, 1972.
Astr. Ap., 24, 411, 1973.
Astr. Ap., 29, 231, 1973.
Ap. J., 190, 525, 1974.
Photometry: (Variable Stars, Cepheids)
Ap. J., 151, 825, 1968.
Photometry: (Bright Blue Stars, Sequences)
Ap. J., 191, 603, 1974.
Distance Modulus:
Ap. J., 151, 825, 1968.
Ap. J., 191, 603, 1974.
Ap. J., 168, 327, 1971.
Rotation Curve and Mass Determination:
Astr. Ap., 7, 210, 1970.
Astr. Ap., 24, 405, 1973.
Astr. Ap., 24, 411, 1973.
HII Regions:
Ann. Ap., 28, 698, 1965 = Publ.O.H.P., 7, No. 50,
"Atlas and Catalogue", Univ. of Washington, Seattle, 1966.
Ap. J., 155, 417, 1969.
Ap. J., 190, 525, 1974.
H{alpha} Interferometry: Astr. Ap., 7, 210, 1970.
SN1954J (described as a very blue variable)
Ap. J., 151, 825, 1968
P.A.S.P., 84, 844, 1972.
HI 21cm:
Ap. J., 142, 616, 1965.
Ap. J., 150, 8, 1967.
Ap. J., 166, 265, 1971.
Ap. J., 176, 315, 1972.
Astr. Ap., 1, 10, 1969.
Astr. Ap., 24, 405, 1973.
Astr. Ap., 24, 411, 1973.
Radio Observations:
Astr. Ap., 29, 231, 1973.

25. 1973UGC...C...0000N
Re:UGC 03918
SAB(s)cd (de Vaucouleurs), Sc+ (Holmberg)
Possible SN 1910 (probably illusory, emulsion defect)

26. 1964RC1...C...0000d
Re:NGC 2403
In the M81 Group.
NGC 2404 is a detail.
Bright middle.
No bright nucleus,
or it has an extremely small nucleus, or a star.
Many, well resolved, irregular arms.
Broad bar.
Ap. J., 51, 287, 1920.
Ap. J., 56, 200, 1922.
Ap. J., 91, 531, 1940.
Medd.Lund II, 128, 1950.
HII Regions:
Observatory, 79, 54, 1959.
Zeit. fur Ap., 50, 168, 1960.
Radio Emission:
P.A.S.P., 72, 368, 1960.
HI Emission:
A.J., 66, 294, 1962.
A.J., 67, 437, 1962.

27. 1961Hubbl.B...0000S
Re:NGC 2403
Nov. 6/7, 1950
103aO + GG1
30 min
Enlarged 2.0X
NGC 2403 is similar in form and in stellar content to M33.
It is a member of the M81 group. The distance modulus
is about (m-M) = 27.1 (A. J., 59, 180, 1954). This is the
first galaxy beyond the Local Group in which Cepheid variable
stars were found with the 200-inch. Twenty-seven
variables have been isolated so far (1960). Ten of them
are definitely Cepheids with periods ranging from 18 to
54 days. Many of the others are undoubtedly Cepheids,
but periods are not yet available. No novae have been
found in NGC 2403. The comparison of the number of
novae found in M81 (Sb) and in NGC 2403 (Sc) shows
that the same disparity exists as between M31 and M33,
and probably indicates that novae are very infrequent in
Sc galaxies as compared with Sb.
Over 100 HII regions, many of them irregular in shape,
are known in NGC 2403. The largest of the regions measures
20 sec of arc in diameter, which corresponds to 270 parsecs
at the assumed distance. This diameter is a bit smaller
than that of NGC 0604 in M33 and considerably smaller
(by a factor of 2.3) than 30 Doradus in the LMC. NGC 2403
and other members of the M81 group are important
for the calibration of the extragalactic distance scale.

28. 1918PLicO..13....9C
Re:NGC 2403
Vol. VIII, Plate 17. A bright, beautiful spiral 16'x 10'. No nucleus apparent;
many almost stellar condensations; of the general type of M. 33. 7 s.n.

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