GPT-6 Astra Minor: What It Is, and Why Sol Became the Middle Tier

3-Line TL;DR

GPT-6 Astra Minor is an unannounced name from an Azure config file, with no price, spec or date, and it was gone from that file when I checked on September 28
The lineup changed more than the leak suggests, with Sol dropping from GPT-5.6 flagship to GPT-6 middle tier and Terra disappearing while Sol took over its "balance intelligence and cost" line
Opus 5.5 beat Astra on three of five scored rows in Anthropic's own table at 40% of the price, and DevDay on September 29 is OpenAI's next chance to answer

On September 22, a user on the Chinese developer forum locdd.com found three unannounced OpenAI model paths in Azure's public playground config (OrcaRouter)
They were gpt-6-sol, gpt-6-luna and gpt-6-astra-minor
Sol and Luna are now live on OpenAI's API (OpenAI models)
Astra Minor has no price, context window, benchmark or announcement, and neither Microsoft nor OpenAI has confirmed it
When I opened the same Azure file on September 28, it listed gpt-6-astra, gpt-6-sol and gpt-6-luna, with no astra-minor
The line may be gone because the model was cancelled, renamed or simply tidied out of the config

GPT-5.6 Sol, Terra, Luna next to GPT-6 Astra, Sol, Luna, with Sol moved from top to middle and Astra Minor as a dashed slot

Sources: OpenAI models and OpenAI pricing, standard short-context rates checked September 28, 2026 — diagram by HSL

GPT-5.6 had a tidy sun, earth and moon lineup
OpenAI called GPT-5.6 Sol its "flagship model for complex professional work" (OpenAI)
GPT-5.6 Terra was "designed for workloads that balance intelligence and cost" (OpenAI)
For GPT-6, OpenAI's guidance says to "choose GPT-6 Sol to balance intelligence and cost"
Terra is gone, and its job description now belongs to Sol
I would have kept Sol, Terra and Luna and put Astra on top, which would tell buyers more than "Astra Minor" does
GPT-6 Sol is cheaper than GPT-5.6 Sol, at $2 / $10 against $4 / $20
That is also exactly what Anthropic charges for Sonnet 5 (Anthropic)
Astra lists at five times GPT-6 Sol on both input and output
A model in that gap would make commercial sense, though that is my guess and not anything OpenAI has said

Bar chart of five benchmarks: Opus 5.5 leads Humanity's Last Exam, Terminal-Bench 4.0 and FrontierCode; Astra leads two rows

Source: Anthropic — Claude Opus 5.5 benchmark table, vendor-reported — chart by HSL

Astra launched on September 3, and Opus 5.5 on September 22
In Anthropic's table, Opus 5.5 leads Humanity's Last Exam by 10.5 points and Terminal-Bench 4.0 by 8.5
FrontierCode is close to a tie, 54.4% to 53.3%
Astra keeps AutomationBench by 1.4 points and Terminal-Bench-Science by 5.9
Opus also leads GDPval-AA v2.1, 1846 to 1542
Anthropic picked the benchmarks and ran its own side, so read this as a vendor report card rather than a neutral test
Astra lists at $10 / $50 and Opus at $4 / $20
On this table, Astra loses most rows and still costs 2.5 times as much
Price per token is not the whole bill, since Opus still cost more on one of two rounds in the Astra vs Opus 5.5 same-prompt test

My view is that OpenAI needs a GPT-6.1 soon more than another tier name
I found no credible GPT-6.1 report, only this Astra Minor leak
OpenAI DevDay is Tuesday, September 29, at Fort Mason in San Francisco, with a 10 a.m. keynote by Sam Altman (DevDay)
The event page promises "a closer look at what OpenAI teams are building" and names no model
Anthropic says Sonnet 5.5 and Haiku 5.5 will follow "in the coming weeks" (Anthropic)
If Sonnet 5.5 keeps Sonnet 5's price, it lands in the same $2 / $10 slot as GPT-6 Sol

Your situation	What I would do
Using Astra for hard back-end or science work	Keep it, since Astra still leads the automation and science rows
Paying Astra rates for routine coding	Test Opus 5.5 on the same tasks and compare cost per finished task
Waiting for Astra Minor to save money	Try GPT-6 Sol now, because Astra Minor has no price or date
Still on GPT-5.6 Sol	Check GPT-6 Sol first, which lists at half the price

In the Astra Minor leak thread, an r/codex user asked how it would differ from Sol and got the reply “minor difference” (Reddit)
In another r/codex thread, an API user said Astra cost more than Opus 5.5 for document and code reviews, without sharing a matched cost log (Reddit)
A reviewer in the same thread used Astra Low alongside Opus 5.5 High and said Astra still caught tricky cases (Reddit)

Q. Can I call Astra Minor through the API?
- No, it is not in OpenAI's model list, and the Azure entry was gone when I checked on September 28
Q. Is GPT-6 Sol the successor to GPT-5.6 Sol?
- By name yes, by role no, since GPT-6 Sol is now the middle tier under Astra
Q. What happened to Terra?
- GPT-6 has no Terra, and OpenAI's catalog now gives Sol Terra's old "balance intelligence and cost" line
Q. Is GPT-6.1 coming at DevDay?
- Nothing says so, and the event page names no model