SN 2002ap in M74

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(CCD image by Y. Sano, when the SN is still rising!)

(CCD image by G. Masi, when the SN is still rising!)

(We have observed SN2002ap using the Caltech Astronomy Department's 14" telescope, in Meade filters which approximate V and R. Conditions were relatively poor, with significant cloud cover and sky glow from Pasadena, CA.

Attached are .gif files of the observations, each image is a combination of 3 x 2 minute exposures. Only dome flats were used in the reduction, hence the gradient across the frame. SN is marked by green cross. Star 1 (GSC1205.789) was used as reference for crude aperture photometry, taken to be V=13.3, R=12.9. Corresponding magnitudes for Star 2 (GSC1205.1059) were measured at V=13.9, R=13.6.

With this reference, SN2002ap is measured at V=13.1, R=13.2.

Approximate mean exposure time in V was UT 02:46:16, 2002-2-2.
Approximate mean exposure time in R was UT 02:34:07, 2002-2-2.

-Rob Simcoe
 Josh Bloom)

Dear SN watchers,

A SN in M74 is discovered by Japanese amateur Yoji Hirose at mag 14.5 (on Jan 29.4) and rising (mag 13.7 on Jan. 30.38). Latest SN in Messier object is SN 1999gn in M61. If this new object is of type Ia, it can become mag 11, the brightest SN since SN 1993J in M81.

Because I have no time for further noting, I give here the location only: R.A. = 1h36m23s.85, Decl. = +15o45'13".0 (2000.0, the KAIT result), which is about 258" west and 108" south of the face-on spiral (SA(s)c) galaxy M74 = NGC 628 in Pisces. The KAIT image can be seen at: , and the chart can be found at AAVSO: .

Sincerely Yours,

Hitoshi Yamaoka, Kyushu Univ., Japan

Spectroscopy : unusual event!

Dear SN watchers,

I have submitted an article (below) to CBAT. SN 2002ap is a unique object!

K. Kinugasa, H. Kawakita, Gunma Astronomical Observatory (GAO); K. Ayani, T. Kawabata, Bisei Astronomical Observatory (BAO); and H. Yamaoka, Kyushu University, write: "Low-resolution spectra of SN 2002ap (IAUC 7810) are obtained on Jan 31.4 UT with GAO 0.65-m telescope (with GCS, range 380-750 nm) and on Jan 31.5 UT with BAO 1.01-m telescope (range 470-700 nm). Preliminary reduction reveals rather blue continuum with a steep decreace over 650-700 nm, and without any deep absorption or emission. Very broad (FWZI ~ 30 - 50 nm) and shallow depressions exist around 570 nm (deepest), 470 nm, and 620 nm. Overall feature resembles to that of a peculiar Ib/c SN (or "hypernova") 1997ef, but SN 2002ap is much bluer. The follow-up observation in all wavelength is strongly recommended for this unusual and nearby exploding object. The spectra can be seen at: and .
Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan


This information was announced on IAUC 7811, as well as other two spectrum (ESO and Wise Obs.), both of which reached the same conclution, i.e., SN 2002ap is a HYPERNOVA !

The intensive followup observation of this unique and very nearby hypernova is strongly encouraged.

Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan

Sequence information

SN 2002ap seems brightening further. Y. Sano, Nayoro, Hokkaido, reports that it is mag 13.41 on Jan. 31.363 UT (unfiltered, compared with USNO-A2.0 rmag). It is surely rising.

The new object locates on the outermost region of the spiral arm. There are many foreground stars superimposed on and around M 74. SN 2002ap locates between GSC 1205.789 and GSC 1205.744. Sano's image ( will help the identification, as well as images in D. Bishop's page: , and .

The comparison stars with V magnitude (measured by A. Henden) is available at AAVSO site , or Tycho-2 Vmag based one is available at: , which are very useful for a visual and V-filtered CCD observers. The unfiltered CCD observer, however, should use R magnitude or such. Temporary, USNO_A2.0 rmag would help.

              Henden-V USNOrmag note
GSC 1205.1059   13.9    13.5    2' west of SN
GSC 1205.789    13.3    12.9    1' west of SN
The distance measure of M74 is about 29.5. The preliminary analysis of the spectrum (See vsnet-alert 7120) reveals very unusual feature, which resembles to that of "hypernova"! The follow-up observation in all wavelength is surely, strongly, highly recommended for this unique and very interesting exploding object!
Sincerely Yours,
Hitoshi Yamaoka, Kyushu Univ., Japan

Radio detection (from GCN)

NUMBER:  1237
SUBJECT: Type Ib/c SN2002ap (SN/GRB?) Radio Observations
DATE:    02/02/01 04:39:22 GMT
FROM:    Edo Berger at Caltech  
E. Berger, S. R. Kulkarni, and D. A. Frail report on behalf of the Caltech-NRAO-CARA GRB collaboration:

"On 2002, February 1.03 UT we used the VLA at 8.46 GHz to observe the position of the peculiar Type Ib/c SN2002ap in M74 (IAUC 7810 and 7811). We detect a radio source with a flux density of 375+/-30 microJy within 1" of the optical position of this supernova at coordinates (J2000): RA=01:36:23.920, DEC=15:45:12.867, with an uncertainty of approximately 10 milliarcsec in both coordinates. The optical spectrum of this SN is similar to that of SN1998bw, and there is some evidence that SN2002ap is a younger and/or more energetic version of SN1998bw (IAUC 7810). In view of the peculiar properties of this object, the radio detection, and the possible connection of SN 1998bw with GRB 980425, we urge further observations at all wavelengths."

NUMBER:  1238
SUBJECT: Type Ib/c SN2002ap (SN/GRB?)
DATE:    02/02/01 04:55:22 GMT
FROM:    Edo Berger at Caltech  
S. R. Kulkarni and E. Berger report on behalf of the Caltech-NRAO-CARA GRB collaboration:

"The early detection of radio emission from SN 2002ap (GCN 1237) has a number of interesting ramifications. Given the distance modulus of M74 of 29.3, the absolute magnitude of the SN is -15.6, and given that the optical emission is still rising (IAUC 7810) it is safe to assume that we are seeing the SN before maximum. The optical spectroscopy suggests an age of 7 days based on analogy with SN 1998bw (IAUC 7811). Adopting this age and a typical expansion speed of 30,000 km/s the inferred brightness temperature in the 8.5 GHz band is 3x10^10 K using the 0.4 mJy detection of Berger, Kulkarni and Frail (GCN 1237). As in the case of SN 1998bw, such a high brightness temperature argues for mildly relativistic expansion (see Kulkarni et al. 1998, Nature, 395, 663). If so, we should expect strong X-ray emission from inverse Compton scattering of the optical SN photons as well as measurable angular diameter of 0.2 milliarcsecond, both of which are verifiable with Chandra and VLBA observations. In addition to these observations, high frequency (sub-mm and mm) observations are also required to find the synchrotron self absorption frequency, which is essential for calculating the energy in the relativistic blastwave (see Kulkarni et al. 1998, Nature, 395, 663). Finally, it would be worthwhile inspecting archival data from gamma-ray burst monitors from the past two weeks to search for a faint GRB in the same position."

Bishop's page

I'm trying to gather everything on this SN at:

I also created a sub page at:

I will try to archive all of the VSNet data on this SN on this page.

Chart by Reinder Bouma/Edwin van Dijk

We have placed a finderchart (2.0 x 2.5 degrees field) of this bright SN with comparison stars down to magnitude 12.6 selected from Tycho-2, just in case it is type Ia, at the following URL:

A f-chart (15x15') with Arne Henden's 1-night photometry and comparison stars fainter than magnitude 12.1 is available at the AAVSO-site (

Reinder Bouma/Edwin van Dijk

Chart by Japan Variable Star Study Association

Link to the chart

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