Re: cluster obs requirements

From: marek kowalski (mpkowalski@lbl.gov)
Date: Fri Jan 27 2006 - 12:06:57 PST

  • Next message: Tony Spadafora: "help with references in proposal"

    Well, technically there are four z band exposures, but the exposure
    time is not distributed equally between i and z. So the sentence on
    page 6 seems correct but might be miss-leading.

    Marek

    On Jan 27, 2006, at 12:02 PM, Marc Postman wrote:

    > OK then we should correct the proposal text on page 6 which currently
    > states:
    >
    > (each orbit contains four ACS/F850LP dithered cosmic-ray splits plus
    > one ACS/F775W exposure)---
    >
    > That looks like 4:1 to me. So the four in the above sentence should be
    > three! Good catch!
    >
    > Marc
    >
    > On Jan 27, 2006, at 2:54 PM, marek kowalski wrote:
    >
    >> Hello Marc,
    >>
    >> I just want to make sure we phrase it consistently. In the SNe
    >> observing requirement section we say 515 seconds exposure in I and
    >> 340 seconds in the four z-band exposures. That makes a ratio of
    >> 1:2.64. The waek lensing section says 25% to 75% which is close
    >> enough to this ratio but different from 4:1.
    >>
    >> Cheers,
    >>
    >> Marek
    >> On Jan 27, 2006, at 11:43 AM, Marc Postman wrote:
    >>
    >>> Here are our expected photometric errors in i775 and z850 - as Henk
    >>> knew, the 4:1 exposure ratio for z850:i775 yields comparable errors
    >>> at
    >>> each AB mag interval. these are based on scaling our Lynx (z=1.27)
    >>> mosaic exposures to the exptimes we will have in our co-added data. I
    >>> am modifying the cluster obs reqs section accordingly and making the
    >>> CMR slope/scatter measurements the main drivers.
    >>>
    >>> <SNeHST_photerr_vs_mag.eps>
    >>> On Jan 27, 2006, at 2:07 PM, Saul Perlmutter wrote:
    >>>
    >>>> ...and of course, show that our new F775 exposures (515 sec times ~7
    >>>> or 8 orbits co-added) is exactly what we need!
    >>>>
    >>> -----------------------------------------------------------------
    >>> Marc Postman Email: postman@stsci.edu
    >>> STScI - CMO Phone: +1-410-338-4340
    >>> 3700 San Martin Drive Fax: +1-410-338-4424
    >>> Baltimore, MD 21218 U.S.A. http://www.stsci.edu/~postman
    >>>
    >>>
    >>
    >> --------------------------------------------------------------
    >> Marek Kowalski Lawrence Berkeley National Laboratory
    >> mpkowalski@lbl.gov 1 Cyclotron Road, MS 50R5008
    >> (510) 486 4652 Berkeley, CA 94720-8160
    >> --------------------------------------------------------------
    >>
    >>
    > -----------------------------------------------------------------
    > Marc Postman Email: postman@stsci.edu
    > STScI - CMO Phone: +1-410-338-4340
    > 3700 San Martin Drive Fax: +1-410-338-4424
    > Baltimore, MD 21218 U.S.A. http://www.stsci.edu/~postman
    >
    >

    --------------------------------------------------------------
    Marek Kowalski Lawrence Berkeley National Laboratory
    mpkowalski@lbl.gov 1 Cyclotron Road, MS 50R5008
    (510) 486 4652 Berkeley, CA 94720-8160
    --------------------------------------------------------------

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