UTC+09:00 explained

Utc:

yes

UTC+09:00 is an identifier for a time offset from UTC of +09:00.

During the Japanese occupations of British Borneo, Burma, Hong Kong, Dutch East Indies, Malaya, Philippines, Singapore, and French Indochina, it was used as a common time with Tokyo until the fall of the Empire of Japan.

As standard time (year-round)

Principal cities: Tokyo, Osaka, Nagoya, Fukuoka, Yokohama, Sapporo, Hiroshima, Kyoto, Seoul, Busan, Daegu, Gwangju, Ulsan, Incheon, Pyeongyang, Yakutsk, Koror, Dili, Jayapura, Ambon

North Asia

Russia – Yakutsk Time^[1]
- Far Eastern Federal District
  - Amur Oblast, Sakha Republic (western part; west of the Lena River as well as territories adjacent to the Lena on the eastern side)^[2]
  - Zabaykalsky Krai

East Asia

Japan – Japan Standard Time
North Korea – Korea Standard Time
South Korea – Korea Standard Time

Oceania

Micronesia

Palau

Southeast Asia

East Timor – Time in East Timor
Indonesia – Eastern Indonesia Time^[3] ^[4]
- Eastern zone, including:
  - Maluku Islands
    - Maluku
    - North Maluku
  - Western New Guinea

Discrepancies between official UTC+09:00 and geographical UTC+09:00

Areas in UTC+09:00 longitudes using other time zones

This concerns areas within 127°30′ E and 142°30′ E longitude.

China

Parts of Northeast China, including eastern half of Heilongjiang Province and Yanbian Korean Autonomous Prefecture in Jilin Province, where is used.

Australia

The easternmost parts of Western Australia where UTC+08:00 is used, Eucla and nearby areas where (unofficial) is used.
The Northern Territory, where is used, and South Australia and Broken Hill where UTC+09:30 and DST are used, respectively, despite the borders of the territory and state fitting perfectly within the ideal meridians of UTC+09:00.
The western parts of Queensland where is used, and westernmost parts of Victoria and New South Wales where UTC+10:00 and in summer time, is used.

Federated States of Micronesia

Parts of Federated States of Micronesia, including western parts of Yap State, where UTC+10:00 is used.

Papua New Guinea

The very westernmost parts of Papua New Guinea, where UTC+10:00 is used.

Russia

Parts of Russia, including Jewish Autonomous Oblast, Primorsky Krai, central part of Sakha, and most of Khabarovsk Krai where UTC+10:00 is used, and westernmost parts of eastern Sakha Republic and Sakhalin Island, where UTC+11:00 is used.

Areas outside UTC+09:00 longitudes using UTC+09:00 time

Areas between 97°30′ E and 112°30′ E ("physical" UTC+07:00)

Russia
- A westernmost part of Sakha Republic, including the urban localities Aykhal and Udachny

Areas between 112°30′ E and 127°30′ E ("physical" UTC+08:00)

Russia
- Zabaykalsky Krai
- Most of western Sakha Republic
East Timor
Indonesia
- The western islands in the provinces of Maluku and North Maluku (from south to north):
  - Liran Island
  - Wetar Island
  - Kisar Island
  - Ambelau Island
  - Buru Island
  - Sanana Island
  - Mangole Island
  - Taliabu and surrounding islands
Japan
- Parts of Okinawa Prefecture:
  - Sakishima Islands
    - Yaeyama Islands
    - Miyako Islands
  - Okinawa Islands
    - Kume Island
    - Aguni Islands
    - The western parts of Kerama Islands
North Korea
- The western parts of Korea, including the capital city, Pyongyang
South Korea
- The western parts of Korea, including the capital city, Seoul

Areas between 142°30′ E and 157°30′ E ("physical" UTC+10:00)

Japan
- The eastern parts of Hokkaido, including Obihiro, Kushiro, and Nemuro
- Minami-Tori-shima in Ogasawara municipality
Russia
- - - - New Siberian Islands Novaya Sibir Faddeyevsky Island
        
        A smaller part of Kotelny Island The eastern part of Great Lyakhovsky Island

Notes and References

Web site: Russia Time Zones - Russia Current Times . TimeTemperature.com. 14 July 2012.
Web site: Sakha – Western, Russia Time Zone. TimeTemperature.com. 25 March 2018.
Web site: Indonesia Time Zones – Indonesia Current Time. TimeTemperature.com. 27 October 2012.
Web site: Provinces of Indonesia. Gwlliam Law. Statoids. 27 October 2012.