IRSOL observing programs and interactions with data collected by space missions

Renzo Ramelli and IRSOL collaborators

IRSOL Locarno, Switzerland

Oslo, Norway

8th August 2013

Outline

• IRSOL observatory and telescope• ZIMPOL polarimeter

• Examples of selected recent observing programs• Examples of Interaction with space observations• Perspectives of IRSOL

IRSOL (Istituto Ricerche Solari Locarno)

Switzerland

Zurich

Is a medium sized telescope (45 cm) still interesting for science?

• To test and develop instrumentation and observing methods that can be transferred to other larger facilities (e.g. ZIMPOL@Gregor)

• More flexibility in the observing time schedule (synoptic programs, reaction to particular solar events)

• Exploit particular telescope characteristics, e.g. for IRSOL:– Instrumental polarization easy to handle

– Low amount of stray light

Telescopelayout

The IRSOL instrumentation

Telescope • Telescope: Gregory - Coudé, evacuated – Diameter of primary mirror: 45 cm– Total focal length: 25 m

• Spectrograph:focal length: 10 mgrating 18 cm × 36 cm 316 lines / mmblaze 63°

• Fabry Perot:Bandwidth ~ 30 mANovel configuration with FP+spectrograph

• ZIMPOL polarimeter (see next slides)

• Adaptive optics:Tip-tiltDM with 37 actuators

ZIMPOL polarimeter

• ZIMPOL-polarimeter (Zurich Imaging Polarimeter) allows precise full Stokes measurements free form seeing induced spurious effects (modulation 42 kHz / 1kHz).

• Basic principle: high frequency modulation, demodulation with dedicated special CCD

• Polarimetric accuracy depends primarily on photon statistics. 10-5 level can be reached with long enough exposure time.

ZIMPOL - setup

ZIMPOL3 microlenses

ZIMPOL3New generation camera system which is now used for observations at IRSOL (Ramelli et al. 2010, SPIE proc.)

ZIMPOL3

• more flexible and compact system• adaptable to different CCD-chips

– new larger CCD for UV with microlenses

• more efficient and faster• based on newer technology

(replace components available on the market)

• more functions (different demodulation schemes, electronic compensation of telescope polarisation offset, ...)

Major improvements:

Other recent improvements in the instrumentation

• Prisma pre-disperser substituted by filter-wheel with high transmission filters

• New electronics for control of spectrograph

• Limb tracker based on slit jaw image (circle fit of the limb)

• Automatic scripts for routine observations

• Soon → new Ag coating

Second solar spectrum observationsSynoptic program(see Kleint et al. 2010, A&A)

Monthly observations at different

- Position angles (N, NW, W, SW, S)- C2

lines at 5140 A

Slit parallel to the limb, at µ=0.15 (10“ from limb)

Are there variations with the solar cycle?

N

S

Examples of on-going projects:

Example of scattering polarization observation of C2 lines

R R R

P

1 2 3

Observation of faint emission lines in prominences (Ramelli, Stellmacher, Wiehr, Bianda et al. 2012, Solar Phys.)

HeII

Inversion of prominence profiles with HaZel code

(HaZel code: Asensio Ramos, Trujllo Bueno and Landi degl’Innocenti, ApJ, 2008)

(Ramelli et al.)

Examples of on-going projects:

Example of interaction with space observations

• (Non)-observation of the impact polarization in solar flares in the Hα line.

(Bianda et al. 2005, A&A).

• Any clear signal detected above sensitivity of 10-3

Simultaneous observation of 5247/5250 Fe and 6301/6302 Fe line pairs

(Stenflo, Demidov, Bianda, Ramelli, 2013, A&A)

Perspectives at IRSOL

• Financing: now ok

• Soon new manpower (1-2 staff + 1 postdoc)

• Give contributions for polarimetry at large telescopes (e.g. ZIMPOL@Gregor → first test campaign foreseen in October 2013)

• Continue high precision spectropolarimetry at IRSOL with improved instrumentation

Thanks for your attention!