Date and Time of the Query: 2019-06-26 T14:13:30 PDT
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Notes for object NGC 3660

15 note(s) found in NED.

1. 2008MNRAS.390.1241B
Re:NGC 3660
4.4 NGC 3660 As there have been no observations of NGC 3660 with XMM-Newton or
Chandra, we use the ASCA observation and its documentation in the Tartarus
catalogue. The ASCA spectrum is fitted well by a power law with no absorption
above the Galactic column Fig. 3 shows the light curve for the 26 ks
observation which shows significant variability on short time-scales.

2. 2008MNRAS.390.1241B
Re:NGC 3660
5.2.2 NGC 3660 The X-ray variability of this source on short time-scales and
unabsorbed profile of its X-ray spectrum leads us to the conclusion that we are
genuinely viewing the nucleus of NGC 3660 directly. This leads us to believe
that NGC 3660 also lacks a BLR as we believe with NGC 3147. However, the origin
of the X-ray variability is not necessarily nuclear as variability was recently
discovered in the ultra-luminous X-ray (ULX) source, M82 X-1 (Mucciarelli et al.
2006). A Chandra observation of NGC 3660 should be able to resolve any ULXs as
we have shown for NGC 4501. We also cannot rule out differential variability as
the cause of the mismatch, as Bianchi et al. (2008) did for NGC 3147. As has
been observed in other X-ray variable Seyferts (e.g. NGC 4151, Gaskell & Sparke
1986), the broad line flux has also been seen to vary. If the broad line flux is
observed in its low state, the object will be seen as type 2, despite being
unobscured. NGC 3660 will also need to be observed simultaneously in the optical
and in the X-rays to rule out this possibility.

3. 2007A&A...461.1209D
Re:NGC 3660
NGC 3660: The BeppoSAX data were not published before. No absorption in
excess to that of the Galaxy has been measured in the 2-10 keV band. The
source is detected in the PDS. Nonetheless, the measured 20-100 keV flux
is well above what is predicted extrapolating the spectrum observed
below 10 keV at these energy. No strong hard X-ray emitters are known to
be within the BeppoSAX fov. The stronger ones are 1AXG J112342-0851 and
1AXG J112237-0847 (Ueda et al. 2001), detected in the 2-10 keV band with
ASCA. In the 2-10 keV band, these sources are ~10 and 20 times fainter
than NGC 3660, thus it seems unlikely that they are responsible for the
excess observed in the PDS, also considering that 1AXG J112342-0851 has
a flat spectrum ({GAMMA} ~ 1.2) accordingly with the hardness ratio
measured by ASCA GIS (Ueda et al. 2001). Assuming that the PDS excess is
due to NGC 3660 emission, the best-fit model is composed by an
unabsorbed power law dominating the emission between 2-10 keV and by an
absorbed one (N_H_ ~ 2.5 x 10^24^ cm^-2^) arising at E >= 10 keV. Thus the
source would be classified as a Compton-thick one. Nonetheless it is
noticeable that no iron emission line is detected at all with an upper
limit on the EW <= 230 eV, thus not in accordance with the detected
absorbing column.

4. 2004MNRAS.353.1151S
Re:NGC 3660
NGC 3660. Has been studied in H I by Richter & Huchtmeier (1987) and
Fisher & Tully (1981) as well as being part of a H I extragalactic data
base observed by Bottinelli et al. (1990). In addition to this it is
also part of a survey to establish the radio properties of bright
Seyferts (Giuricin et al. 1990) and a H_2_0 megamaser survey (Braatz,
Wilson & Henkel 1996). Its radio continuum has also been studied as part
of a survey of southern Seyfert by Morganti et al. (1999).

5. 2002PNAOJ...6..107M
Re:KUG 1121-083
Thin blue arms + red bar.

6. 2002A&A...389...68G
Re:NGC 3660
NGC 3660: the catalog of HII regions is quite poor and the values of
PA and IA are not very well constrained. Nevertheless, the two methods
are in good agreement and in rough agreement with the photometric
values from RC3 (1991). We adopt the mean of our two methods.

7. 1999A&AS..140....1M
Re:NGC 3660
NGC 3660 (Mrk 1291)
A strong bar is seen in the K' image of this galaxy (Fig. 8a) but the
ring is barely visible. On the other hand, both the bar and ring appear
clearly on the sharp-divided image (Fig. 8b).
The edges of the bar can also be seen in the difference image (Fig.8c);
the bar parameters are determined from Fig. 8e. From an R image,
Chapelon et al. (1999) give PA = 116^deg^ out to 16 arcsec for the bar.
This agrees with Friedli et al. (1996) who show that bars are generally
longer in K than in R.
The J/K' color image (Fig. 8d) shows a smooth structure, increasingly
red towards the center, and a steep central gradient (Fig. 8h). The bar
region also appears redder than the surroundings. The color map also
shows clear hints of the existence of a small, red circumnuclear
Due to the large size of this galaxy, the bulge + disk decomposition is
not reliable (Fig. 8f), as confirmed by the high residuals (Fig. 8g).

8. 1999A&AS..137..457M
Re:NGC 3660
NGC 3660: This object is unresolved in our observations. The source was
previously detected by the Effelsberg 100 m telescope (Kollatschny et
al. 1983). The total flux measured in our observation (0.5 mJy) is much
smaller than that reported by Kollatschny et al. (11 mJy). The reason
for this discrepancy is likely to be the presence of other two bright
unrelated sources in the field. These sources could not be separated
from NGC 3660 by the 100 m telescope but they are in our VLA data.

9. 1999A&AS..135..437G
Re:MRK 1291
Mark 1291. Spectroscopic observations of this barred spiral by
Kollatschny et al. (1983) show it to be a "transition object" between
Seyfert 2s and H II regions; however, high excitation lines
characteristic of Seyfert 2s such as [Fe XIV]{lambda}5303 and [Fe X]
{lambda}6374 are detected. The nuclear emission is compact (Gonzalez
Delgado et al. 1997). Our optical spectra show a weak broad (FWHM ~ 1950
km s^-1^) H{alpha} component suspected by Kollatschny et al. The narrow
lines are well fitted with a single Gaussian profile (~160 km s^-1^
FWHM). The line ratios are {lambda}5007/H{beta} = 3.84,
{lambda} 6300/H{alpha} = 0.04 and {lambda}6583/H{alpha} = 0.73
(significantly larger than the published value, 0.48); the
classification of this object is therefore ambiguous: it is a
Seyfert 2 in the the {lambda}5007/H{beta} vs. {lambda}6583/H{alpha}
diagram and a H II region in the {lambda}5007/H{beta} vs.
{lambda}6300/H{alpha} diagram. It would be of interest to obtain
high-resolution, high signal-to-noise spectra of this object to
confirm its "transition" nature.

10. 1998AJ....116.2682C
Re:IRAS 11210-0823
NGC 3660, Mrk 1291. Seyfert 2. Optical position from Kojoian et al.
(1981). Radio source heavily resolved with the C configuration.

11. 1997ApJS..108..155G
Re:NGC 3660
NGC 3660 has an S2 compact nucleus in H{alpha} and [O III] in an SBbc
host galaxy. The disk shows 59 H II regions in a ring and along the
spiral arms. The H II regions in the outskirts of the galaxy are of much
higher excitation than those in the ring, in particular two of them
located to the northeast direction at 40" and 50" from the nucleus; this
is seen clearly in the [O III] map shown in Figure 11f. At 40" to the
southwest there is a group of faint regions forming a shell structure.

12. 1993ApJS...86....5K
Re:NGC 3660
NGC 3660 (Mrk 1291); SBbc, mini-Seyfert 1, NELG.
This galaxy is classified, on the basis of the optical spectrum, as
between a Seyfert 1 and a narrow emission line galaxy (NELG) (Kollatschny
et al. 1983). Nevertheless, the UV spectrum looks like that of a normal
SBbc galaxy with no nonthermal activity. This galaxy, with z = 0.012,
shows strong Ly{alpha} emission.

13. 1976RC2...C...0000d
Re:NGC 3660
m{_pg} = 12.5 in MCG, Vol. III, 1963.

14. 1974UGCA..C...0000N
Re:UGCA 234
UGCA 234:
= NGC 3660
several small almost stellar objects nearby,
probably background group or cluster

15. 1963MCG3..C...0000V
Re:MCG -01-29-016
On its periphery to the northeast there are 4 companions 18 mag - 19 mag.

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