From: Rachel Gibbons (rachel.a.gibbons@vanderbilt.edu)
Date: Mon Dec 20 2004 - 10:31:26 PST
Hi Tomas,
About the Dolphy (acs04c-014) NICMOS measurements for the NE knot
being 2 mags off... Yes, they are, I screwed up. Here are the new
numbers, which have also been transferred to the Wiki page. This should
help a great deal sorting this one out. I sadly hadn't gain-corrected,
which, for the NICMOS data, means 1.83 mags.
|band |e-/s |corrected mags|
|F110W|0.2720(0.0729)|26.154(0.291) |
|F160W|0.1456(0.0394)|26.032(0.294) |
The numbers for Mingus (acs04-076) are correct.
Rachel
On Mon, Dec 20, 2004 at 02:05:01PM +0100, Ariel Goobar wrote:
>
> >From Tomas...
> --
> ___________________________________________________________________
> Ariel Goobar (www.physto.se/~ariel)
> Department of Physics, Stockholm University
> AlbaNova University Center, SE-106 91 Stockholm, SWEDEN
> tel: +46 8 55378659 fax: +46 8 55378601
>
> ---------- Forwarded message ----------
> Date: Mon, 20 Dec 2004 13:47:22 +0100
> From: Tomas Dahlen <dahlen@physto.se>
> To: Ariel Goobar <ariel@physto.se>
> Subject: host galaxy phot-z
>
> Hi,
>
> here are some results on the phot-zs for the host galaxies to Mingus,
> Dolphy & Alice C.
> I also attach three plots with the probability distributions for each host.
>
> *****Mingus*********
> SE knot: z=1.46
> NW knot: z=1.58
> SW knot: z=1.65
> all, 0.75 arcsec aperture: z=1.59
> all, 1.05 arcsec aperture: z=1.62
>
> I guess that the 1.05 arcsec should be the best. For the knots, there
> are probably
> systematic errors since these magnitudes are not corrected for the small
> aperture
> size used (0.18 arcsec, different filters shuold have different
> corrections, affecting the
> phot-z measurements).
>
> *****Dolphy*********
> 1) NE knot, 0.30 arcsec aperture: z=1.75
> 2) SW knot, 0.30 arcsec aperture: z=2.00
> 3) all, 0.78 arcsec aperture: z=1.66
>
> 1) NE knot has NICMOS photometry (which the other don't) . This does,
> however, not fit any template well.
> It seems that the NICMOS photometry is 1-2 magnitudes too faint. Maybe
> an aperture effect? Don't trust this
> phot-z (or the plotted probability distribution)!
> 2) Again, small aperture may bias result.
> 3) I would trust this the most, despite the lack of NIR.
>
> *****ALICE COLTRANE*********
> phot-z: 0.46
>
> This host only has photometry in three bands (VIz), which makes the
> phot-z determination difficult, resulting in a broad probability
> distribution.
> Besides the best fit at z=0.46, there is also a second peak in the
> probability
> distribution at =0.8, which is almost as strong as the lower z peak.
>
>
> /Tomas
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