1 / 29

Spitzer-IRAC/Akari-IRC Cross-Calibration

Spitzer-IRAC/Akari-IRC Cross-Calibration. Jason Surace April 19, 2007. With figures by Ohyama, Wada, and Tanabe.

lala
Download Presentation

Spitzer-IRAC/Akari-IRC Cross-Calibration

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Spitzer-IRAC/Akari-IRCCross-Calibration Jason Surace April 19, 2007 With figures by Ohyama, Wada, and Tanabe

  2. It is in the overall interest of IRAC to ensure that the calibration of Akari is consistent with IRAC’s. This will allow direct comparison between datasets on both satellites, and along the way ensure we haven’t made any major errors. IRC has capabilities Spitzer doesn’t. It has more broadband filters, and spectroscopic capabilities down to 1.5 µm. Our Interest in Akari (formerly Astro-F, formerly IRIS)

  3. Brief Akari Overview Much like Spitzer: 68 cm telescope, this satellite is not small! 4m long, 960kg! Imaging and Spectroscopy

  4. Sun-synchronous Earth orbit 68cm telescope 3.7m, 960kg 170l He, 1.8 yrs 1.8-160µm Primarily all-sky survey Earth-trailing Solar orbit 86cm telescope 4.4m, 950 kg 350l He, 5.5 yrs 3.6-160µm Primarily pointed observations

  5. IRC and FIS 10x10’ imaging 2,3,4,7,9,11,15,18,24,60,160µm Low-res slit and slitless spectroscopy over entire wavelength range IRAC, IRS, and MIPS 5x5’ imaging ~4,5,6,8,24,70,160 µm, plus some minimal 16µm Low and high-res slit spectroscopy over 5-40µm Low-res spectroscopy 50-100µm

  6. Post-Cryo! Spitzer: IRAC 3.6 and 4.5µm channels will continue working. Passive cooling. Akari: IRC NIR channel, with 2, 3, 4µm filters plus spectroscopy will continue to work. Passive cooling plus cryo-coolers.

  7. Equivalent of JPL+Goddard Runs all space science missions (I.e. everything). Development, assembly, operations, research, etc. 250 total people. Akari looks to be operated by 10-20 people, total.

  8. IRC Spectroscopic Capabilities

  9. NIR N2 (1.7-2.7µm) ~10 min stack single1-min observation

  10. NIR (InSb) NP Prism (2-6µm)

  11. MIR-L Si:As LG2 Grism (17-25µm)

  12. Akari Calibrator Stars Akari calibration methodology identical to IRAC’s. Martin Cohen generates predicted fluxes based on instrument throughput and templates. Broad-band imaging and spectroscopy both calibrated in this fashion. Almost all Akari calibrators already observed by IRAC. Mostly A & K-stars. Deliberate overlap with IRAC to extent allowed by pointing constraints.

  13. Some Difficulties Difficult to use the slits due to pointing issues. Advantages to using slitless (easier to handle slit loss), but there are confusion problems at short wavelengths. Also, wavelength calibration not fixed and leads to problems near spectrum ends.

  14. Near-IR Prism 2MASS 1757132 KF06T2 - K-star Note - calibration is set by this object at short end. Black is Cohen template, blue is IRC data.

  15. Near-IR Grism BP +66 1073 - K-star HD 42525 A-star (calibrator) KF09T1 K-star

  16. <NP>K vs. A(in mJy*um^2 unit) K A 2MASS 1757132 KF06T2 <base>

  17. <NG>K vs. A(in mJy*um^2 unit) K A <base>

  18. Unfortunately, this is confused by the fact that we don’t have the raw spectra, only the flux-calibrated ones which already have the standard star response in them. But you can see the absorption trough in channel 2 easily!

  19. <SG1>K vs. A (in mJy*um^2 unit) K A <base>

  20. Mid-IR Short Grism 1 BP +66 1073 K-star HD 42525 A-star (calibrator) NPM 1p67 536 K-star

  21. Mid-IR Short Grism 2 BP +66 1073 K-star HD 42525 A-star (calibrator)

  22. For at least some K-stars, Martin’s templates have too deep troughs. But they work well for other stars. Inadequacy of optical spectral typing? No obvious surprise features. Still need to get raw data. Getting any data has been tricky. Are We Learning Anything?

  23. Akari CVZ within 0.6 degrees of ecliptic pole (similar to WISE), vs. 4-5 for Spitzer. All Akari cal stars located within their northern and southern CVZ. Deep survey at ecliptic caps. Ideal for general cross-cal with IRAC. IRAC dark field outside the Akari CVZ, although it is being observed in a fashion as part of a mission project (Egami, PI). Observing Akari cal field as an IRAC cal activity. Akari Calibration Locations

  24. “Deep” Component Central 5x5’ Depth is 28x100 seconds 5-sigma = 0.6, 1.2, 7.5, and 9 µjy at 3.6, 4.5, 5.8, and 8 µm. Confusion-limited at 3.6 and 4.5µm. 2 hours to execute.

  25. “Shallow” Component Coverage of a 10x10’ area with all 4 arrays. 8x30 seconds = 2x SWIRE integration time 5-sigma = 2.5, 4.2, 28, and 32µJy at 3.6, 4.5, 5.8, 8 µm. High Dynamic Range Mode 50 minutes to execute

  26. Akari NEP Cal Field Observed by IRAC Ch.1 Ch.4 Ch.1 Entire Field, all exposures

  27. IRAC vs. IRC Broadband Photometry

  28. Computed the expected slopes from Martin’s model calculations for specific stars. IRC/IRAC numbers match to within 5%, the limit I could measure them to. Somewhat circular, since Akari also calibrated to Cohen templates. Indicates no significant issues with system throughput measurements. Indicates that point source measurement and calibration methodology holds and agrees between missions. Early Results from Cross-Cal Field Encouraging

More Related