2. Expected performance

The expected performance of KOOLS-IFU mounted on Seimei telescope is described below.

Note: KOOLS-IFU has neither the imaging nor the slit-spectrocopy mode.

# Spatial Performance (see also this page)
(after 2020/Oct.)

Number of fibers	117 (= 110 for objects and 7 for sky)
FoV of a fiber	regular hexagon of 0.42 arcsec inradius
Fiber pitch	0.84 ± 0.07 arcsec
Total FoV	8.4 x 8.0 arcsec for object and 2.5 x 2.4 arcsec for sky FoV for aladin (vot file). Please see like here for usage.
Fiber core filling factor	~100%

(before 2020/Sep.)

Number of fibers	127
FoV of a fiber	0.93 ± 0.04 arcsec diameter (design: 0.91 arcsec)
Fiber pitch	1.16 ± 0.05 arcsec (design: 1.14 arcsec)
Total FoV	15.1 ± 0.7 arcsec diameter (design: 14.8 arcsec)
Fiber core filling factor	58%

# Spectral Performance
(after 2020/Oct.)

Grism	VPH-blue	VPH-red^†	VPH 495	VPH 683^†	LS 656^‡
Wavelength coverage	4100-8900 Å	5800-10200 Å	4300-5900 Å	5800-8000 Å	5700-7500 Å
Spectral resolution	~500	~800	~1500	~2000	~2200
Total peak throughput*	~13.3%	~10.7%	~8.7%	~7.1%	~7.9%

throughput@2022/07/22 & 2025/03/18

†: in normal observations, use an order-sorting filter O56, which blocks < 5600 Å light
‡: with the bandpass filter, which blocks < 5500 and > 8000 Å light for order sorting and suppressing stray lights.
*: including the effects of telescope and atmosphere at Zenith (airmass=1).

(before 2020/Sep.)

Grism	VPH-blue	VPH-red^‡	VPH 495	VPH 683^‡
Wavelength coverage	4100-8900 Å	5800-10200 Å	4300-5900 Å	5800-8000 Å
Spectral resolution	~500	~800	~1500	~2000
Total peak throughput^†	5.6%	4.7%	4.3%	3.0%

†: including the fiber core filling factor at the 2D array (58%)
‡: in normal observations, use an order-sorting filter O56, which blocks < 5600 Å light

# CCD

Overhead time per exposure	16 seconds
Recommended exposure time	1-1800 seconds (integer only)
Linearity	~1% or better
Saturation count	65535 ADU (plan)

# Other information

Typical time of grism change

10-20 seconds