Discussion on beams

Page last updated, FXD, CK, 2015-11-02 Figures to be redone

We measure the beam by using the middle scan of the 3-scans sequence launched with @beammap Here are the best-of on 3 sources.

Preliminary findings

The main beam (the Gaussian part) seems with a normal width aka 11", 17" (but only in single-pixel analysis). The maps show broader beams of 13", 19.5" (see Table below).
The quadrupod holding the secondary gives clear diffraction marks as a faint cross at about -30dB, visible in all Mars scans. Uranus and 3C83 are not bright enough to reach -30dB. To go deeper, we need Saturn or Jupiter maps.
In between, there is a large near-side lobe, especially at 2mm (but also visible at 1mm), that shows up as a rectangular pyramid-like shape at the 10% level, the origin of which is unknown. It seems to scale with wavelength. It was not so apparent in NIKA. Therefore the quality of the dichroic is not at the center of this issue.
For comparison, see the NIKA-1 beam maps in Fig.8 of Catalano+2014 and in Fig.8 of Monfardini+2011.

Source	Date/Scan	HPBW	HPBW
		1mm	2mm

Mars || 20151030s73 || 12.9 || 19.3 || Mars || 20151031s88 || 12.7 || 19.6 || Uranus || 20151029s217 || 14.5 || 19.5 || Uranus || 20151030s174 || 13.2 || 19.7 || 3C83 || 20151030s51 || 14.3 || 19.4 ||

Beams on Mars

20151030s73
20151031s88

Beams on Uranus

20151029s217
20151030s174

Beams on 3C84

20151030s51

-  ⇤ ← Revision 10 as of 2015-11-02 11:45:14 → 
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+   ← Revision 15 as of 2015-11-02 14:42:35 → ⇥
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- * The main beam (the Gaussian part) seems with a normal width aka 11", 17".
+ * The main beam (the Gaussian part) seems with a normal width aka 11", 17" (but only in single-pixel analysis). The maps show broader beams of 13", 19.5" (see Table below).
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- * The quadrupod holding the secondary gives clear diffraction marks as a faint cross visible in all scans.
+ * The quadrupod holding the secondary gives clear diffraction marks as a faint cross at about -30dB, visible in all Mars scans. Uranus and 3C83 are not bright enough to reach -30dB. To go deeper, we need Saturn or Jupiter maps.
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+|| Source || Date/Scan || HPBW || HPBW ||
|| || || 1mm || 2mm ||
Mars || 20151030s73 || 12.9 || 19.3 ||
Mars || 20151031s88 || 12.7 || 19.6 ||
Uranus || 20151029s217 || 14.5 || 19.5 ||
Uranus || 20151030s174 || 13.2 || 19.7 ||
3C83 || 20151030s51 || 14.3 || 19.4 ||
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 * 20151031s88
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 * 20151030s174

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Diff for "OffProcNika2Run1Beam"