SN 2006X

Bruce L. Gary (GBL)
Hereford Arizona Observatory (G95)

This web page is meant to record my observations of SN 2006X. It includes reference stars for BVRI observations.

Links Internal to this Web Page
    Overview
    Light Curve
    Photometric Sequence

Overview

When SN 2006X was discovered 2006.02.07.1 by Shoji Suzuki there was speculation that the SN was 2 weeks BEFORE maximum and that it would increase in brightness to possibly 11 th magnitude. This potentially dramatic event, coupled with the fact that it was a Type Ia SN (the type used to establish that the universe expansion is now accelerating) motivated me to mount an aggressive campaign to perform 4-filter monitoring of its evolving color. I wanted an accurate photometric sequence and the 5 Brian Skiff stars nearby were for BV only, and I wasn't sure how accurate even these two magnitudes were. So I began by performing a 4-filter "all-sky" photometric calibration of the stars near the SN (using Landolt star fields, which are the "gold standard" for photometrists). The all-sky photometry was successful (validating the Skiff magnitudes to the 0.02 magnitude level). After the second day of observing the SN I could tell that it would never reach 11th magnitude, and that in fact it was already close to maximum. By the 4th day I suspended observing this SN. I'ms still waiting for that next bright SN to be discovered 2 weeks edore maximum. For waht it's worth (not much, in my opinion), hwere's what I've got for this SN.

Here's a color image of M100 showing the SN.
  

Figure 1. False color image of M100 (using IRV instead of RGB). FOV = 8.5 x 7.6 (crop of larger image). 2006.02.11 UT. Note that bright stars are saturated and appear white regardless of their color.  [Hereford Arizona Observatory, Celestron 14-inch, SBIG ST-8XE CCD, LVRI total exposure times are 12, 16, 20 and 14 minutes; digital development.]

Light Curve

These are my observations of SN 2006X. They have all been "transformed" to correct for my telescope system's unique response to star color.

Light curve

Figure 2. Light curve for SN 2006X.

                                                TABLE I

                                                SN 2006X BVRI Measurements


 B
 V
 R
 I
 B-V
Msc Comments
2006 FEB 10.3
15.08



2006 FEB 11.3
 16.12 +/- 0.04
 14.91 +/- 0.03 14.13 +/- 0.03 13.77 +/- 0.05
 1.21 +/- 0.05
2006 FEB 12.3
 16.06 +/- 0.04
 14.67 +/- 0.03
 14.01 +/- 0.05
 13.52 +/- 0.03
  1.39 +/- 0.05
All-sky cal'n
2006 FEB 13.3 15.91 +/- 0.05
 14.54 +/- 0.05
 13.75 +/- 0.04
1.37 +/- 0.07





















Notice that SN 2006X has B-V = 1.39 +/- 0.05. This means it's very red. Unfiltered measurements are going to be too bright unless they're "CCD transformed."

Photometric Sequence

The following is my "photometric sequence" based on observations of nearby Landolt stars 2006.02.12 UT.

                                          TABLE II   Reference Star BVRI Magnitudes

Star #
 B
 V
 R
 I
1
 14.73 +/- 0.03
 14.12 +/- 0.03 13.77 +/- 0.03
 13.40 +/- 0.03
2
 14.80 +/- 0.03 14.05 +/- 0.03 13.68 +/- 0.03
 13.36 +/- 0.03
3
 13.78 +/- 0.03 13.12 +/- 0.03 12.77 +/- 0.03
 12.43 +/- 0.03
4
 16.68 +/- 0.05 16.11 +/- 0.04 15.75 +/- 0.03 15.44 +/- 0.04
5
 13.40 +/- 0.03 12.91 +/- 0.03 12.63 +/- 0.03 12.33 +/- 0.03
6
 16.37 +/- 0.04
 15.18 +/- 0.03 14.39 +/- 0.03 13.65 +/- 0.05
7
 16.94 +/- 0.05
 15.73 +/- 0.03 15.01 +/- 0.03 14.41 +/- 0.03
 
Reference stars

Figure 3. BVRI magnitudes dervied from observations of Landolt stars on the same observing night as these stars were assigned BVRI magnitudes. FOV = 15.2 x 10.1 'arc. [Hereford Arizona Observatory, Celestron 14-inch, SBIG ST-8XE CCD, unfiltered, total exposure of 12 minutes; digital development.]

All stated uncertainties are SE (stochastic plus systematic). I note that stars 1, 2, 3, 5 and 6 are listed in a Skiff catalog with B and V magnitudes. My magnitudes differ from Skiff's by -0.01 +/- 0.02 (for B) and +.02 +/- 0.01 (for V). In other words, we agree!

Other people's observations for this SN can be found at SNWeb2.

Here's a Very Large Telescope (ESO) false color mage:

VLT

Related Links

    Bruce's AstroPhotos
    All-Sky Photometry Tutorial
    Simplified Magnitude Equation Tutorial

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This site opened:  February 11, 2006.  Last Update:  March 2, 2006