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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"

495 results found.

  1. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  2. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  3. EP 250108A: Late-time optical observation by LCO
  4. EP250111a: Swift/XRT detection and fading
  5. EP250111a: NOT likely optical counterpart
  6. EP250111a: a new X-ray transient detected by Einstein Probe
  7. EP250108a: further NOT optical observations
  8. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  9. EP250108a: EP-FXT follow-up observation
  10. The EP-WXT trigger 01709130111 is likely a flaring star
  11. EP250109a: Swift/UVOT non-detection
  12. EP250108a: Liverpool Telescope likely optical counterpart
  13. EP250109a: Swift/XRT non-detection
  14. EP250109a: EP-WXT detection of an X-ray transient
  15. EP250108a: EP-WXT detection of an X-ray transient
  16. The EP-WXT trigger 01709129925 is likely a flaring star
  17. GRB 241229A: SVOM/VT optical upperlimit
  18. EP241231b: optical upper limit with the Liverpool Telescope
  19. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  20. EP241217a: VLA Radio Detection

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

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