Bootes
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# Bootes: Validation Report (FULL)

Bootes: Validation Report (FULL)¶

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Master catalogue used: __master_catalogue_bootes_20180111.fits__<br>Number of rows: 3,388,482<br>Surveys included:<br>​| Survey    | Telescope / Instrument      |      Filters (detection band in bold)      | Location                    ||-----------|-----------------------------|:------------------------------------------:|-----------------------------|| NDWFS     | MOSAIC                      | R, I, Bw, Ks                               | dmu0_NDWFS                  || DECaLS    | Blanco/DECam                | g,r,z                                      | dmu0_DECaLS                 || PS1 3PSS  | Pan-STARRS1 / Pan-STARRS1   | g,**r**,i,z,y                              | dmu0_PanSTARRS1-3SS         || zBootes   | 90prime                     | z                                          | dmu0_zBootes                || Legacy Survey | BASS                    | g, r, z                                    | dmu0_LegacySurvey           || IBIS      | NEWFIRM                     | J,H,Ks                                     | dmu0_IBIS                   || UHS       | UKIRT/WFACM                 | J                                          | dmu0_UHS                    || DataFusion| Spitzer / IRAC              | **IRAC1**,**IRAC2**,**IRAC3**,**IRAC4**    | dmu0_DataFusion- Spitzer    || SDWFS     | Spitzer/IRAC                | IRAC1, IARC2, IRAC3, IRAC4                 | dmu0_SDWFS                  |

Master catalogue used: master_catalogue_bootes_20180111.fits
Number of rows: 3,388,482
Surveys included:

Survey	Telescope / Instrument	Filters (detection band in bold)	Location
NDWFS	MOSAIC	R, I, Bw, Ks	dmu0_NDWFS
DECaLS	Blanco/DECam	g,r,z	dmu0_DECaLS
PS1 3PSS	Pan-STARRS1 / Pan-STARRS1	g,r,i,z,y	dmu0_PanSTARRS1-3SS
zBootes	90prime	z	dmu0_zBootes
Legacy Survey	BASS	g, r, z	dmu0_LegacySurvey
IBIS	NEWFIRM	J,H,Ks	dmu0_IBIS
UHS	UKIRT/WFACM	J	dmu0_UHS
DataFusion	Spitzer / IRAC	IRAC1,IRAC2,IRAC3,IRAC4	dmu0_DataFusion- Spitzer
SDWFS	Spitzer/IRAC	IRAC1, IARC2, IRAC3, IRAC4	dmu0_SDWFS

## I. Caveats

I. Caveats¶

### I.a. Magnitude errors

I.a. Magnitude errors¶

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At faint magnitudes (mag > 24), some surveys have very large errors on the magnitude. These objects may be unreliable for science puposes.<br>This includes __DECaLS aperture and total__ magnitudes (at mag > 26), __PanSTARRS aperture nad total __ magnitudes (at mag > 23), __BASS aperture and total__ magnitudes (at mg > 23), __NDWFS total__ magnitude (at mag > 25 for R and I, anf mag > 14 for Ks), __IBIS aperture and total__ magnitudes (at mag > 23) and __IRAC1 aperture and total__ magnitudes (at mag > 23).<br>​<img src="help_plots/Bootes_magVSmagerr_DECAM_g_mag_total.png" />​

At faint magnitudes (mag > 24), some surveys have very large errors on the magnitude. These objects may be unreliable for science puposes.
This includes DECaLS aperture and total magnitudes (at mag > 26), PanSTARRS aperture nad total magnitudes (at mag > 23), BASS aperture and total magnitudes (at mg > 23), NDWFS total magnitude (at mag > 25 for R and I, anf mag > 14 for Ks), IBIS aperture and total magnitudes (at mag > 23) and IRAC1 aperture and total magnitudes (at mag > 23).

### I.b. Aperture corrections

I.b. Aperture corrections¶

CDFS-SWIRE_apcorrIssues_OmegaCAM_z_aperture_-_GPC1_z_aperture.png
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In most of the case when comparing the aperture magnitudes between surveys, we observed a two peak distribution in the difference between the magnitudes ($\Delta_{mag} = mag_{survey1} - mag_{survey2}$). We have one peak around 0 for point-source objects, with a small spread. And a second peak at higher $\Delta_{mag}$ with a larger spread for extended objects; implying a different aperture correction between surveys for these objects.<br>That means that galaxies will not have the same aperture magnitude in different surveys. <br>​In the griz bands, for bright sources, there is a two peaks distribution when comparing Pan-STARRS, DECaLS, BASS and NDWFS aperture magnitues. Except between BASS and DECaLS where $\Delta_{mag}$ is similar for point-source and extended objects.<br>​<img src="help_plots/Bootes_apcorrIssues_BASS_g_aperture_-_GPC1_g_aperture.png" />

In most of the case when comparing the aperture magnitudes between surveys, we observed a two peak distribution in the difference between the magnitudes ( $\Delta_{mag} = mag_{survey1} - mag_{survey2}$ ). We have one peak around 0 for point-source objects, with a small spread. And a second peak at higher $\Delta_{mag}$ with a larger spread for extended objects; implying a different aperture correction between surveys for these objects.
That means that galaxies will not have the same aperture magnitude in different surveys.

In the griz bands, for bright sources, there is a two peaks distribution when comparing Pan-STARRS, DECaLS, BASS and NDWFS aperture magnitues. Except between BASS and DECaLS where $\Delta_{mag}$ is similar for point-source and extended objects.

## II. Flags

II. Flags¶

### II.a. Pan-STARRS aperture magnitude

II.a. Pan-STARRS aperture magnitude¶

 
Few Pan-STARRS sources have exactly the same error (of <font color='blue'>0.0010860000038519502</font>) on the __aperture and total__ magnitudes in all the grizy bands. The corresponding aperture magnitude should not be trusted for these objects.<br>​<img src="help_plots/Bootes_gpc1Issues_GPC1_g_mag_aperture.png" />

Few Pan-STARRS sources have exactly the same error (of 0.0010860000038519502) on the aperture and total magnitudes in all the grizy bands. The corresponding aperture magnitude should not be trusted for these objects.

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### II.c IRAC aperture magnitude​IRAC bands are available in this field, but there are no sources with exactly the same magnitude (as it is the case in some other fields with IRAC observations).

II.c IRAC aperture magnitude¶

IRAC bands are available in this field, but there are no sources with exactly the same magnitude (as it is the case in some other fields with IRAC observations).

### II.b. Outliers

II.b. Outliers¶

CDFS-SWIRE_outliers_OmegaCAM_g_aperture_-_GPC1_g_aperture.png
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By comparing magnitude in the same band between different surveys, we can see that some magnitudes are significanlty different could not be trusted. <br>The outliers are identified to have a large weighted magnitude difference (equivalent of the $chi^2$).​$$chi^2 = \frac{(mag_{1}-mag_{2})^2}{magerr_{1}^2 + magerr_{2}^2}$$ <br>We used the 75th and 25th percentile to flagged the objects 5$\sigma$ away on the large values tail of the $chi^2$ ditribution. (__NB:__ bright sources tend to have their errors underestimated with values as low as $10^{-6}$, which is unrealistic. So to avoid high $chi^2$ due to unrealistic small errors, we clip the error to get a minimum value of 0.1% (i.e. all errors smaller then $10^{-3}$ are set to $10^{-3}$).)<br><br>$$outliers == [chi^2 >  (75th \;percentile + 3.2\times (75th \;percentile - 25th \;percentile))]$$​<img src="help_plots/Bootes_outliers_DECAM_g_aperture_-_GPC1_g_aperture.png"/>​​

By comparing magnitude in the same band between different surveys, we can see that some magnitudes are significanlty different could not be trusted.
The outliers are identified to have a large weighted magnitude difference (equivalent of the $chi^2$ ).

c h i^{2} = \frac{(m a g_{1} - m a g_{2})^{2}}{m a g e r r_{1}^{2} + m a g e r r_{2}^{2}}

$chi^2 = \frac{(mag_{1}-mag_{2})^2}{magerr_{1}^2 + magerr_{2}^2}$
We used the 75th and 25th percentile to flagged the objects 5

σ

$\sigma$ away on the large values tail of the

c h i^{2}

$chi^2$ ditribution. (NB: bright sources tend to have their errors underestimated with values as low as

10^{- 6}

$10^{-6}$ , which is unrealistic. So to avoid high

c h i^{2}

$chi^2$ due to unrealistic small errors, we clip the error to get a minimum value of 0.1% (i.e. all errors smaller then

10^{- 3}

$10^{-3}$ are set to

10^{- 3}

$10^{-3}$ ).)

o u t l i e r s == [c h i^{2} > (75 t h p e r c e n t i l e + 3.2 \times (75 t h p e r c e n t i l e - 25 t h p e r c e n t i l e))]

$outliers == [chi^2 > (75th \;percentile + 3.2\times (75th \;percentile - 25th \;percentile))]$

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