Monday, February 25, 2019

Why is dawn in Indonesia too early? (5)

For long, some astronomers have a presumption that the light pollution (in addition to air pollution) might delay the presence of dawn. In this fifth video, based on the real astronomical data, we proved that the presumption is groundless. 

ISRN-UHAMKA used an SQM to collect the sky-brightness data in two different places in Yogyakarta on May 5 and 6, 2018. The data collection took place in two different places, Krakal Beach and Panguk Hill when the moon phase was a waning gibbous moon, only 4-5 days after the full moon. 

The estimated dips from the SQM data on these two days were -16.7 degrees and -15.1 degrees, in spite of the fact that the sky was highly light polluted. The illuminated parts of the moon were 78% and 70% respectively. The above-mentioned dips are much deeper than the average dip of -13.3 degrees estimated from 206 days of the SQM data.

To verify the results, we used a high-resolution DSLR camera Nikon D5100 capable of producing an image with more than 16 million pixels. Some image processing techniques confirm the presence of the SQM's dawns. Therefore, the present Fajr call is really too early. Please, check the enclosed video. 

Previous video:

1) Why is dawn in Indonesia too early? (1)
2) Why is dawn in Indonesia too early? (2)

3) Why is dawn in Indonesia too early? (3)
4) Why is dawn in Indonesia too early? (4)

Tuesday, February 19, 2019

Why is dawn in Indonesia too early? (4)

ISRN has been using four sensors to detect the presence of dawn to mark the commencement of the Fajr prayer for Muslims in Indonesia. The main instrument is a Sky Quality Meter (SQM) which records the sky-brightness data. In the first video, we demonstrated the use of 198 data for the Fajr and 149 data for the Isha to conclude that the dawn actually occurs when the sun is at the dip of -13.3 degrees, not at -20 degrees like what we have been practicing for tens of years. This simply implies that our Fajr call is actually about 26 minutes too early. On the contrary, the Isha call is about 26 minutes too late. The latter might not be as crucial as the former one. However, it is becoming dangerous for those who perform their Maghreb prayer too late because the timings might have belonged to the Isha time.

In our second video, we showed a verification process using an All Sky Camera (ASC) to detect the presence of the real dawn, whilst in the third video, a verification process by an independent third party is explained.

In this fourth video, we used a low-cost gadget camera to verify the presence of the real dawn. All these verification processes further confirm that the SQM detected dawn is compliant with the actual physical data. Please check the above video.

Previous video:

1) Why is dawn in Indonesia too early? (1)
2) Why is dawn in Indonesia too early? (2)
3) Why is dawn in Indonesia too early? (3)

Monday, February 11, 2019

Why is dawn in Indonesia too early? (3)

On August 21, 2017, The Jakarta Islamic Center (JIC) in Jakarta invited us to present our interim results regarding the issue of the presence of dawn before an assembly of experts from different expertise. There were around 80 invitees which are generally sharia experts (hadith, interpretation, Islamic Astronomy, etc.). 

Two days later, on August 23, 2017, JIC sent its dawn observation team to photograph the dawn on Pramuka Island, Thousand Islands Regency. For this, the JIC observation team used an ordinary DSLR camera. This video explains the verification process by the third party. Visually, the JIC observation team did not witness the presence of dawn when the Fajr prayer call was echoed by the local mosque at 4:41, the official timing as suggested by the government. The team only confessed to witnessing the presence of dawn at about 5:15 which is about 14 minutes late as the estimated dawn using the SQM data occurred at 5:00:54. 

Furthermore, image processing analyses of the imageries taken by the team show that the real dawn only occurred at 5:20 which is 19 minutes later than the dawn calculated using the SQM data. This simply proves that the SQM sensor is apparently much more sensitive than the naked eyes. However, this report further convinced us that with better geometric and temporal resolutions, a DSLR camera might be a good instrument to verify the presence of dawn in the future. If this is of interest to you, please follow this link:

Previous video:

1) Why is dawn in Indonesia too early? (1)
2) Why is dawn in Indonesia too early? (2)

Friday, February 1, 2019

Why is dawn in Indonesia too early? (2)

ISRN-UHAMKA has been using five different sensors to detect the presence of dawn, although we have concluded that the SQM is actually our main instrument. As you will see from the following video presentations, SQM is a very versatile instrument for such tasks.

In this second video, ISRN-UHAMKA is presenting a verification process of the presence of dawn detected by the SQM data using an All Sky Camera (ASC). ASC is a reliable instrument for many environmentalists. It is basically an ordinary DSLR camera equipped with a fisheye lens capable of capturing half of the hemisphere. An Open Fajr Project initiated by Muslims in Birmingham, UK has used an ASC as the main (and the sole) sensor to rectify the commencement of the Fajr prayer.  A Consensus Panel consisting of 19 experts was formed to analyze hundreds of ASC imageries manually (i.e. visually). They conclude that the new dip for Birmingham is -13.4 degrees. It is unclear whether or not this new dip is then adopted by all Muslims in the UK. 

ISRN's approach is different in the sense that we used ASC only for the verification process to confirm the SQM detected dawn. Furthermore, ISRN applied the digital analysis to the ASC images using image processing techniques. Please check it through:

Previous video:
1) Why is dawn in Indonesia too early? (1)