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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

1094 results found.

  1. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  2. EP 250108A: Late-time optical observation by LCO
  3. EP250111a: Swift/XRT detection and fading
  4. EP250111a: NOT likely optical counterpart
  5. EP250111a: a new X-ray transient detected by Einstein Probe
  6. EP250108a: further NOT optical observations
  7. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  8. EP250108a: EP-FXT follow-up observation
  9. The EP-WXT trigger 01709130111 is likely a flaring star
  10. EP250109a: Swift/UVOT non-detection
  11. EP250108a: Liverpool Telescope likely optical counterpart
  12. EP250109a: Swift/XRT non-detection
  13. EP250109a: EP-WXT detection of an X-ray transient
  14. EP250108a: EP-WXT detection of an X-ray transient
  15. The EP-WXT trigger 01709129925 is likely a flaring star
  16. GRB 241229A: SVOM/VT optical upperlimit
  17. EP241231b: optical upper limit with the Liverpool Telescope
  18. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  19. EP241217a: VLA Radio Detection

  20. GRB 241229A: EP-FXT X-ray afterglow confirmation
  21. GRB 241229A: Swift-XRT observations
  22. GRB 241229A: EP-FXT afterglow candidates
  23. EP240702a: 7DT Optical upper limits
  24. EP241223a: EP-WXT detection of a fast X-ray transient
  25. The EP-WXT trigger 01709129287 is likely a flaring star
  26. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  27. EP241217a: optical upper limit with the Liverpool Telescope
  28. GRB 241209B: EP-FXT afterglow detection
  29. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  30. EP241217a: refined EP-WXT analysis and EP-FXT follow-up observations
  31. GRB 241217A / EP241217b: Nanshan/HMT optical upper limit
  32. GRB 241217A / EP241217b: NOT optical upper limits
  33. EP241217a: NOT optical observations
  34. EP241119a: 7DT Optical upper limits
  35. GRB 241209A: ATCA radio follow-up observations
  36. EP241217b/GRB 241217A: EP detection of the prompt X-ray emssion
  37. EP241217a: Swift-XRT Detection
  38. EP241217a: EP detection of an X-ray transient
  39. The EP-WXT trigger 01709129023 is likely a flaring star
  40. The EP-WXT trigger 01709128948 is likely a flaring star
  41. The EP-WXT trigger 01709128921 is likely a flaring star
  42. EP trigger ID 01709128824 is not a real source
  43. EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs
  44. EP241213a/GRB241213a: Likely joint detection and INTEGRAL/SPI-ACS counterpart
  45. EP241213a: EP detection of An X-ray Transient
  46. GRB 241209A: EP-FXT follow-up observations
  47. EP241208a: EP-FXT follow-up observations
  48. EP241206a: 1.5m OSN optical limit
  49. EP241208a: EP detection of a fast X-ray transient
  50. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  51. EP241206a: BOOTES Global Network optical limits
  52. EP241206a: EP detection of a fast X-ray transient
  53. EP241201a: EP-FXT follow-up observations
  54. EP241201a: BOOTES-5 optical upper limit
  55. EP241202b: EP detection of a fast X-ray transient
  56. EP241201a: EP detection of a fast X-ray transient
  57. The EP-WXT trigger 01709126243 is not a real source
  58. The EP-WXT trigger 01709125191 is not a real source
  59. EP241126a: WFST Observations
  60. LIGO/Virgo/KAGRA S241125n: EP-FXT follow-up observations
  61. EP241126a: EP-FXT follow-up observation update
  62. EP241126a: GSP detects optical counterpart
  63. EP241126a: TRT optical counterpart detection
  64. EP241126a: EP detection of a fast X-ray transient
  65. GRB 241113B: EP-FXT afterglow detection
  66. EP241125a: EP detection of an X-ray transient
  67. EP trigger ID 01709122294: the X-ray transient is likely a stellar flare event
  68. EP241119a: GIT optical upper limits
  69. EP241119a: EP detection of a fast X-ray transient
  70. EP241115a/GRB 241115D: Swift/XRT follow-up observation
  71. The EP-WXT trigger 01709120856 is likely a flaring star
  72. EP241113a: Swift XRT weak detection
  73. EP241115a: EP detection of a fast X-ray transient
  74. EP241113b/GRB 241113B: EP detection of GRB 241113B
  75. EP241113a: EP on-board trigger and autonomous follow-up observation
  76. EP241107a: EP-FXT follow-up observations
  77. LIGO/Virgo/KAGRA S241109bn: Upper limits from EP-WXT observations
  78. EP241109a: EP on-board trigger and autonomous follow-up observation
  79. EP241107a: GSP detects optical counterpart
  80. GRB 241105A: EP-FXT follow-up observations
  81. EP241107a: EP on-board trigger and autonomous follow-up observation
  82. EP241104a: EP detection of GRB 241104A X-ray emission
  83. EP241101a: EP-FXT observations update
  84. EP241103a: GIT optical upper limit
  85. EP241103a: Swift XRT detection and improved X-ray position
  86. EP241103a: EP observation update
  87. LIGO/Virgo/KAGRA S241102br: EP-WXT X-ray follow-up and flux limits
  88. EP241103a: GSP optical upper limit
  89. EP241103a: an X-ray transient detected by Einstein Probe
  90. EP241101a: BOOTES-7 optical upper limit
  91. EP241030a: Futher EP-FXT observation of the X-ray Afterglow of GRB 241030A
  92. EP241101a: EP-WXT detection of a fast X-ray transient
  93. GRB 241030A / EP241030a: GMG possible spectroscopic redshift at z ~ 1.4
  94. EP241030a: EP/FXT observation of GRB 241030A X-ray Afterglow
  95. GRB 241030A / EP241030a: FTW Optical and NIR observations of the optical counterpart
  96. EP241030a: EP detection of GRB 241030A X-ray Afterglow
  97. EP241026b: EP-FXT follow-up observation
  98. GRB 241025A: The discovery of a BdHN I from data of Swift, Fermi, SVOM and Einstein Probe telescopes
  99. EP241021a: ATCA radio observations
  100. GRB 241026A Fermi GBM Analysis

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